Research ArticlePharmacokinetic and Tissue Distribution Study of Solid LipidNanoparticles of Zidovudine in Rats

Shah Purvin Parameswara Rao Vuddanda Sanjay Kumar SinghAchint Jain and Sanjay Singh

Department of Pharmaceutics Indian Institute of Technology (Banaras Hindu University) Varanasi 221005 India

Correspondence should be addressed to Sanjay Singh ssinghpheiitbhuacin

Received 31 July 2013 Revised 27 December 2013 Accepted 31 December 2013 Published 19 February 2014

Academic Editor Jeffery L Coffer

Copyright copy 2014 Shah Purvin et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Zidovudine-loaded solid lipid nanoparticles (AZT-SLNs) and zidovudine in solution were prepared and administered in ratsThe aim of this research was to study whether the bioavailability of zidovudine can be improved by AZT-SLNs perorally torats as compared to oral administration of zidovudine Zidovudine was determined in plasma and tissues by reverse phase highperformance liquid chromatographyThepharmacokinetic parameters of zidovudinewere determined after peroral administrationarea under curve of concentration versus time (AUC) for AZT-SLNs was 3125 greater than AZT solution meanwhile meanresident time (MRT) was found to be 183 times higher for AZT-SLNs than AZT solution Elimination half life of zidovudine wasalso increased for SLN formulation Tissue distribution pattern of zidovudinewas changed in case of AZT-SLNs AUCof zidovudinein brain and liver was found to be approximately 273 and 177 times higher in AZT-SLNs thanAZT solution respectively indicatingthatAZT-SLNs could cross blood brain barrier Distribution of zidovudinewas approximately 095 and 086 times lesser in heart andkidney respectively It can be concluded from the study that oral administration of AZT-SLNsmodifies the plasma pharmacokineticparameters and biodistribution of zidovudine

1 Introduction

Zidovudine (31015840-azido-31015840-deoxythymidine AZT) is a nucle-oside reverse transcriptase inhibitor (NRTI) that inhibitsthe replication of the human immunodeficiency virus type1 (HIV) AZT is phosphorylated by cellular enzymes toa 51015840-triphosphate form that interferes with the viral RNAdependent DNA polymerase (reverse transcriptase) andchain elongation of the viral DNA thereby inhibiting viralreplication It decreases the frequency and severity of oppor-tunistic infections improves neurologic function transientlyimproves CD4 T-lymphocyte counts and decreases theserum concentration of HIV antigen Zidovudine therapy issafe and efficacious with limited adverse reactions [1]

AZT is classified under Biopharmaceutical ClassificationSystem (BCS) as a class III drug has a short biological half-life and undergoes extensive first pass metabolism Due tofirst pass metabolism average bioavailability is approximately63 More than 75 of administered dose of zidovudineis metabolized by liver through glucuronidation which is

inactive in nature and remaining 20are excreted unchangedin urine [2 3] Long term therapy of AZT can have severeside effects such as bone marrow toxicity resulting in gran-ulocytopenia and anemia [1] These side effects are dosedependent The toxicity can be reduced by reducing the doseand minimizing the plasma level fluctuation [4 5] Anotherproblem associated with oral antiretroviral therapy is thatthe drug can not efficiently reach the central nervous system(CNS) that acts as an important reservoir of the HIV [4ndash6]Solid lipid nanoparticles (SLNs) are promising drug deliveryfor water soluble drugs to enhance bioavailability Also theincorporation of AZT in SLNs could be developed in orderto directly target the drug Orally administered SLNs reachthe systemic circulation via transcellular transport throughthe enterocyte and phagocytosis of the drugs by mast cellsof Payerrsquos patches lining the intestinal mucosa [3 4] Severalstudies reported that SLNs are also efficient in crossing theblood brain barrier (BBB) It is reported that drug deliveryby SLN through lymphatic system changes pharmacokineticprofile of drug completely [4ndash6]

Hindawi Publishing CorporationJournal of NanotechnologyVolume 2014 Article ID 854018 7 pageshttpdxdoiorg1011552014854018

2 Journal of Nanotechnology

Solidification of lipid nanoemulsion is used to fabricatenanocarrier system Nowadays researchers utilize varioustechnological advances for the preparation of SLN like highshear homogenization ultrasound high pressure homoge-nization (either cold or hot homogenization) solvent emulsi-ficationevaporation and microemulsion method Materialsused in the preparation of SLNs are fatty acids triglyceridesand phospholipids SLN formulations are biocompatible withbody and more stable than liposome also provide sustaineddrug release

The sole aim of this research work was to developand assess pharmacokinetics and biodistribution of orallyadministered zidovudine-loaded SLNs (AZT-SLNs) in ratsThe main reason for the selection of peroral route of admin-istration is because IV or any other routes of administrationare not compatible with treatment involving frequent dosingPreviously several studies with the AZT were done by usingroutes of administration like duodenal and intravenous Nowthis study was focused on comparison of the pharmacoki-netics and tissue distribution of AZT-SLNs and AZT controlsolution after oral administration

2 Materials and Method

21 Materials Zidovudine was donated as a gift sample fromRanbaxy Laboratories Limited Gurgaon India Stearic acidwas purchased from CDH Delhi Tween 80 and polyvinylalcohol (PVA) were purchased from Himedia MumbaiIndia Methanol sodium acetate and glacial acetic acid wereobtained from Qualigens Navi Mumbai India Acetonitrilewas purchased from SD Fine Chem Mumbai India andheparin (Beparin 5000UmL) was from Hyderabad IndiaAll the reagents which were used for the extraction andmobile phase preparation were of HPLC grade and theremaining others were of analytical grade Deionized HPLCgrade water was prepared by Millipore system (Direct-QUV) Separated blank plasma collected from rats was kept atapproximately minus20∘C

22 Methods

221 Preparation of Zidovudine SLN AZT-SLNs were pre-pared according the procedure previously established andoptimized by Dhobal et al [3] in our nanotechnologylab Same methodology was followed for preparation ofAZT-SLNs The SLNs were prepared using wow doubleemulsion solvent evaporation method 300mg of stearicacid was dissolved in 5mL solvent mixture consisting ofdichloromethane methanol (2 3) Twenty milligrams ofAZT was dissolved in 1mL aqueous solution containing0125 vv Tween 80 Both solutions were mixed and son-icated using ultrasonicator (Hielscher Ultrasonic Processormodel number UP200H Germany) for 2min at 60∘C ampli-tude and 05 frequency The primary emulsion obtained wasthen poured into 100mL PVA solution (1 vv) at roomtemperature (25∘C) and stirred for 2 hrs at 1500 rpm SLNswere obtained as the solvent evaporates

222 Nanoparticle Size Analysis and Zeta Potential Measure-ment The zeta potential of the nanoparticles is determinedfrom the measurement of their electrophoretic mobilityand the polydispersity index is a measure of the size dis-tribution of the nanoparticle population Average particlesize polydispersity index and zeta potential of AZT-SLNswere determined in distilled water by the Delsa Nano Cparticle analyzer (Beckman Coulter USA) and the systemwas maintained at 25∘C

223 Total Drug Content (TDC) and Entrapment Efficiency(EE) Total amount of drug in formulation was measured bydissolving 1mL of SLNs formulation in 10mL of methanolThe amount of AZT in each sample was detected spec-trophotometrically (Hitachi U-1800 spectrophotometer) bymeasuring the absorbance of the clear supernatant at 120582max of265 nm ForUV absorbance placebo formulationwas treatedin the same manner as the sample and was used as blankThe given equation was used for the calculation of total drugcontent

TDC = concentration times dilution factor

times volume of formulation(1)

TheEEwas determined bymeasurement of the free drug con-tent in the supernatant obtained after centrifuging AZT-SLNsuspension in high speed cooling centrifuge at 16000 rpmfor 30min at 0∘C using Remi cooling centrifuge (MumbaiIndia) The EE was calculated as follows

EE = total drug (assay) minus free drug

total drug times 100 (2)

224 Stability Study of AZT-SLNs Prepared AZT-SLNs werelyophilized at minus30∘C under vacuum (25mbar) for 24 h ina freeze dryer (Decibel Scientific Industries ChandigarhIndia) using 1ww lactose as cryoprotectant The driedpowder was then kept in glass vials sealed with rubber capsand they were kept under ambient temperature and moisturecondition (25∘C and 60 RH) for a period of 1 2 and3 months Every month the dried powder of the stabilitysamples was redispersed in distilled water and the stability ofthe SLNs was evaluated on the basis of their particle size andthe EE of suspension

225 In Vitro Release Kinetic of AZT In vitro release studywas carried out in pH 68 phosphate buffer by using dialysisbag method using dialysis membrane having molecularweight of 12000ndash14000Da 5mL of prepared formulation wasplaced inside the dialysis bag tied at both ends and dippedin the dissolution medium which was kept at 37 plusmn 02∘Ctemperature with 100 rpm stirring speed 2mL aliquot waswithdrawn at predetermined time intervals of 025 05 1 23 4 6 8 10 12 18 and 24 hr the withdrawn amount wasreplaced by an equal volume of fresh dissolution mediumAliquots were diluted and subjected to spectrophotometricanalysis at 265 nm The unknown concentration of AZT indifferent samples was calculated from the calibration curvewhich was prepared previously

Journal of Nanotechnology 3

226 Pharmacokinetic and Tissue Distribution Study of AZT-SLNs Twelve Charles Foster strain albino rats (200ndash230 gm)of either sex aged about 3 months were selected for thepharmacokinetic study The animals for the study were kepthoused in propylene glycol cages under controlled environ-mental conditions of 25 plusmn 1∘C temperature 45ndash55 relativehumidity and 12-12 h light dark cycleThe rats had free accessto feed and water ad libitum unless otherwise stated in theexperiment Animals were acclimatized for at least one weekbefore using them for experimentsThe rats were divided intotwo groups A and B Rats from group A received 10mgkgAZT solution (1mgmL) and rats from group B received10mgkg AZT-SLN Blood was taken at predefined timeintervals before dose and 15min 30min 45min 90min 2 hr4 hr 6 hr 8 hr 10 hr and 12 hr after dose from retroorbitalplexus under slight ether anesthesia Blood was collected iniced cool heparinized eppendorf tubes Sample preparationwas done as described later All plasma sampleswere analyzedby reversed phase high performance liquid chromatography(HPLC) method The whole study was previously approvedby the Institutional Ethics Committee Institute of MedicalScience Varanasi Uttar Pradesh India

To study the tissue distribution pattern twelve rats of thesame breed of either sex were selected Rats were acclimatizedfor at least one week before using them for experimentsRats were divided into two groups A and B each grouphaving 6 rats Group A rats received 10mgkg AZT solution(1mgmL) and group B received 10mgkg dose of AZT-SLNsRats were then sacrificed by cervical dislocation at 15min30 min 45min 2 hr 4 hr and 6 hr after dosing and heartliver kidney and brain were collected after dosing Tissuesamples were washed with 09wv sterile physiologicalsaline solution and immediately weighed and stored at minus20∘Cuntil HPLC analysis

227 Sample Preparation Protein precipitation method wasused for the determination of AZT in rat plasma Thecollected blood was centrifuged at 3500 rpm (model numberC-24BL Remi Centrifuge India) for 15min at 20∘C tem-perature to separate plasma and it was stored at minus20∘Cuntil the analysis In order to ensure the effective separationof AZT from plasma components by HPLC the plasmawas deproteinized by adding 1mL acetonitrile to 100 120583L ofsample for each plasma sample which was previously spikedwith 50 120583L of AZT solution All plasma samples were thenallowed to stabilize for 30min followed by centrifugationat 15000 rpm for 15min The supernatant was transferredto a tube and evaporated to dryness at 45∘C in nitrogengas atmosphere The residue was reconstituted in 100 120583Lof mobile phase and was injected into the column for thedetection of the AZT (120582max 265 nm)

For tissue distribution study tissue samples were homog-enized in 10mL deionised water and 200 120583L of homogenatewas taken in 2mL eppendorf tube Tissue proteins wereprecipitated by adding acetonitrile up to 2mL Tissue sampleswere allowed to stabilize for 30min and centrifuged at15000 rpm for 15min The supernatant was collected and thepellete was discarded The supernatant was evaporated at

45∘C innitrogen gas streamandwas reconstituted in 100120583Lofmobile phase and injected into the column for the detectionof AZT (120582max 265 nm)

228 In Vivo Quantification of AZT A RP-HPLC system(Waters Corporation Milford MA USA) was used to quan-tify AZT in plasma HPLC (Waters 2998) was equippedwith photodiode array detector set at 265 nm and WatersSpherisorbODS2 column (250mmtimes 460mm ID 5120583mpar-ticle size) associated with guard column (46mm times 30mmID 5120583m particle size) AZT was eluted by isocratic flow at arate of 1mLmin at ambient temperature with amobile phasecomprising a mixture of acetate buffer pH 45 (135mM) andmethanol in the ratio of 75 25

229 Pharmacokinetic Analysis Pharmacokinetic analysiswas carried out by using theWinNonlin 61 Professional soft-ware (Version 53 Copyright 1998ndash2009 Pharsight corpora-tion NC USA) Noncompartmental extravascular analysismethod was employed for the pharmacokinetic parameteranalysis

2210 Statistical Analysis All pharmacokinetic parametersof AZT-SLN and AZT solution were expressed as mean plusmnstandard deviation (SD) The data were analyzed with GraphPad Prism statistical analysis using studentrsquos unpaired 119905-test119875 valueslt005lt001 and lt0001 were considered significant

3 Result

31 Characterization of AZT-SLNs The selection of a partic-ular method of encapsulation is usually determined by thesolubility characteristic of the drug As AZT is hydrophilic innature SLNs were fabricated using wow double emulsionsolvent evaporation method with appropriate modification

The particle size was observed over a range of 600ndash630 nm for the optimized AZT-SLN formulation with poly-dispersity index of 0195 The particle size distribution graphfor the optimized batch is present as Figure 1 The EE of AZTwas found to be 2706plusmn096 for this method Zeta potentialis defined as the electric charge on particle surface whichcreates an electrical barrier and acts as a ldquorepulsive factorrdquoresponsible for the stabilization of nanoparticles The zetapotential of the optimized SLN formulation was found to beminus18mV Here the observed low zeta potential was due to thenonionic nature of the surfactant (Tween 80 and PVA) SinceSLN was stored in lyophilized form zeta potential did notplay significant role in the stability of the SLN There was nosignificant change in the EE after stability studies In vitrorelease study of AZT-SLNs showed burst release followed byslow release which can be attributed to the presence of freedrug in the external phase and the absorbed drug on thesurface of the particles followed by slow release of drug fromthe encapsulated lipid matrix 60 drug was found to beavailable within 2-3 hrs of administration and this release ofdrug may be due to diffusion of drug from the pores on theparticle surface (Figure 2)

4 Journal of Nanotechnology

20

15

10

5

0

100 572 3275 18738 100000

Diameter (nm)

Diff

eren

tial i

nten

sity

()

Intensity distribution100

75

50

25

0

Cum

ulat

ive i

nten

sity

()

Figure 1 Particle size distribution graph of the optimized AZT-SLNformulation

0 4 8 12 16 20 240

102030405060708090

100

Time (hrs)

Dru

g re

leas

e (

)

Figure 2 In vitro release of the optimized AZT-SLN formulation

32 Plasma Pharmacokinetics The mean plasma concentr-ation-time profiles of the AZT-SLNs and AZT solutionare presented in Figure 3 Pharmacokinetic parameters ofAZTwere determinedusing noncompartmental analysis andthey are mentioned in Table 1 As shown at all points inFigure 3 the AZT plasma concentration was higher in ratsadministered with AZT-SLNs than those administered withAZT solution (119875 lt 005) except the first sampling pointThere was no difference in 119879max of AZT when it was givenas SLN The AUC

0ndash119905 value of AZT-SLNs was found to be 128times higher than AZT solution (119875 lt 005) At the same timethe AUC

0ndashinfin value was found to be 131 times higherThe halflife of AZT was significantly increased with AZT-SLNs (119875 lt005)The clearance rates were found to be 2312 and 2985 forAZT-SLNs and AZT solution respectively Compared withAZT solution the mean resident time (MRT) was prolongedwith AZT-SLNs (119875 lt 0001) These results demonstratedthat the incorporation of AZT into SLNs brought about anincreased absorption after oral administration

0 50 100 150 200 250 300 350 400 450 5000

1000

2000

3000

4000

5000

6000

7000

8000

AZT solutionAZT-SLNs

Time (min)

Plas

ma c

once

ntra

tion

(ng

mL)

Plasma concentration profile

Figure 3 Plasma concentration profile of AZT solution and AZT-SLNs

Table 1 Pharmacokinetic parameters for AZT solution and AZT-SLNs formulation

Parameters AZT solution(mean plusmn SD)

AZT-SLNs(mean plusmn SD)

119862max (ngmL) 646421 plusmn 1149076 399221 plusmn 2238821

119879max (min) 1500 plusmn 000 1500 plusmn 000

AUC0ndash119905

(minlowastngmL) 3143067 plusmn 703193 4035763 plusmn 4574343

AUC0ndashinfin

(minlowastngmL) 3212627 plusmn 7531474 4216763 plusmn 5296766

11990512

(min) 8041 plusmn 1215 10541 plusmn 1056

CL(mLminkg) 2985 plusmn 397 2312 plusmn 092

MRT (min) 7701 plusmn 174 14056 plusmn 1475

33 Tissue Distribution of AZT-SLNs The mean concen-tration versus time profile of each tissue for the solutionand SLNs is demonstrated in Figure 4 The 119862max in all fourcollected tissues appeared at 15min after treatment withAZT solution in rats In rats treated with AZT-SLNs the119862max appeared at the same time except in liver and brainin which 119879max was prolonged to 45min and 30min aftertreatment respectively The 119862max in brain of rats was foundto be higher after administration of AZT-SLNs as comparedto AZT solution The ratios of 119862max (AZT-SLNs to AZTsolution) in brain kidney heart and liver were 192 118 089and 075 respectively The AUC

0ndash6 h values were in the orderof kidney gt heart gt liver gt brain for the AZT solution and itwas in the order of kidney gt liver gt heart gt brain for AZT-SLNs The ratios of AZT-SLNs to AZT solution for AUC

0ndash6 hin brain liver heart and kidneywere 273 177 096 and 085

Journal of Nanotechnology 5

Liver

0 50 100 150 200 250 300 350 4000

1000

2000

3000

4000

5000

6000

7000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

AZT solutionAZT-SLNs

AZT solutionAZT-SLNs

Kidney

0 50 100 150 200 250 300 350 4000

3000

6000

9000

12000

15000

18000

21000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Heart

0 50 100 150 200 250 300 350 4000

1000

2000

3000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Brain

0 100 200 300 4000

500

1000

1500

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Figure 4 Mean concentration-time profile of various tissues

4 Discussion

Many formulations have been fabricated to improve the oralbioavailability and brain targeting of AZT Till date controlled[7] and extended [8] release matrix tablet liposomes [9ndash11]microspheres [12 13] nanocapsules [14] nanoparticles [15ndash18] nanospheres [19] thermoreversible gel [20] transdermaldrug delivery system [21] chemical drug delivery system[22] and solid lipid nanoparticle [3] have been proposed fordelivery of AZT Self-assembled drug delivery system alsohas been tried for prodrug delivery of AZT [23] Besidesperoral route various routes like intranasal intravenousand transdermal routes have been tried for targeting drugdelivery Amongst all described routes peroral route ofadministration is considered ideal because of possibility offrequent dosing and patient compliance

Targeting of antiretroviral drug to brain is importantin HIV patients because of ensuing encephalopathy on theprogression of disease AZT simply has not shown any ability

to cross the blood brain barrier The present formulationwas developed for brain targeting and increasing its thera-peutic effectiveness by modifying its pharmacokinetics Wesuccessfully prepared AZT-SLNs for oral administrationThe AUC

0ndashinfin and mean resident time (MRT) of AZT-SLNswere 127 and 183 times that AZT solution respectivelywhile Cl was decreased considerably At the same timethe 119862max of AZT-SLNs formulation was decreased whichindicates the extended release of AZT from SLNs In thepresent study decrease in Cl indicated that the excretionof AZT was delayed when incorporated into SLN Studieshave been reported that SLNs may exhibit bioadhesion tothe gastrointestinal tract wall increasing their residencetime in gastrointestinal tract In addition lipid ingredientused in the formulation of AZT-SLNs increases adhesion ofthe formulation to the intestinal epithelium and enhancespenetration of drug as compared to the solution [24]

After intragastric administration of AZT solutionthe mean peak plasma concentration of AZT was

6 Journal of Nanotechnology

646421 plusmn 114908 ngmL after oral dosing whereasin the case of AZT-SLNs observed mean peak plasmaconcentration was 399221 plusmn 22388 ngmL both appeared at119879max of 15min It was seen during study that 119862max associatedwith AZT-SLNs was less as compared to AZT solution butat the same time the AUC

0ndashinfin associated with AZT-SLNswas significantly higher than AZT solution The reasonbehind this type of kinetic behavior is because of the lipidshell surrounding the drug core which leads to the decreasein instant absorption of drug through stomach which isnot possible in case of simple solution The same is alsohelpful for explaining the extended release pattern whenformulation goes through the intestine Reportedmechanismof absorption of SLNs is mainly through Peyerrsquos patches byintracellular uptake or paracellular pathway The absorptionbehavior in this system is reported to enable bypass of gastricand intestinal degradation of the encapsulated drug and theirpossible uptake and transport through intestinal mucosa[24] It is also reported that adhesive properties due to thelipid shell increases bioavailability and reduces or minimizeserratic absorption [25 26] Despite these discussions nodata has been published so far concerning the stability ofSLNs in the GI tract The change in excretion pattern of AZTwith respect to SLNs is due to the change in distributionpattern of AZT This is due to the lymphatic absorption ofSLNs which leads to decrease in first pass metabolism ofthe drug through hepatic recirculation Significant decreasein clearance (119875 lt 001) and increase in MRT (119875 lt 0001)indicate targeting of drug directly to organs without goinginto systemic circulationThis happened due to the lymphaticabsorption of SLNs from GI tract which is supported by thetissue distribution study [27]

Higher concentrations in various tissues are essential forits pharmacological roles In the present study the ratio of119862max in the brain after administration of AZT-SLNs andAZT solution was 192 and the ratio of AUC

0ndash6 h in thebrain was 273 Based on the previous studies it is reportedthat increasing concentration of AZT in the brain is usefulfor the treatment of dementia associated with HIV uponthe intragastric administration of AZT-SLNs Under normalconditions drug penetration into the brain is restricted bythe blood brain barrier (BBB)Themechanisms for transportof SLNs through the BBB are not completely understoodThe little decrease in ratios of 119862max and AUC

0ndash6 h in heartand kidney indicated that lesser AZT was taken up in thesystemic circulation which helps in reduction of toxicityof AZT like bone marrow suppression The 119879max for AZTsolution and AZT-SLNs were 30 and 45 respectively whichindicates delayed penetration of SLNs into liver leading toincreased effectiveness of formulation by delaying first passmetabolism of drug into the liver Use of AZT-SLNs alsoresulted in decreased concentration of AZT in kidney leadingto slower excretion rate increasing the MRT It is possiblethat lipid associated with AZTmay have altered the excretionprofile because AZT itself being a water-soluble drug hasfaster excretion as compared to AZT-SLNs Graph representsthat distribution of AZT-SLN in brain was biphasic and 119879maxachieved was slower and delayed up to 30min while in caseof AZT solution it was achieved at 15min

When AZT is incorporated into nanoparticles the prop-erties of the SLNs will determine the in vivo disposition ofdrug The clearance of nanoparticles from blood circulationis done by themononuclear phagocyte system (MPS) Resultsindicate that AZT-SLNs might have been taken up in thegastrointestinal tract and translocated to the organs con-taining MPS After intragastric administration of AZT-SLNsthey were rapidly absorbed and distributed well to targettissue that is brain after a single dose administration It alsoexhibited the extended release pattern which was indicatedby its release kinetics Collectively the data indicate that SLNsare a guaranteed delivery system for the enhancement of oralabsorption of zidovudine a water-soluble drug

5 Conclusion

The present study has demonstrated that the intragastricadministration of AZT-SLNs provided prolonged drug deliv-ery and increased the AZT level in brain It can be a potentialformulation for the treatment of HIV Outcomes of this studyhave provided a basis to conduct further studies in HIVpatients

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are thankful to All India Council for TechnicalEducation (AICTE New Delhi India) for their generoussupport of this work Purvin Shah also gratefully acknowl-edges the financial assistance provided by University GrantCommission (UGC New Delhi India) in the form of JuniorResearch Fellowship for the partial fulfillment of the require-ments for the degree of Master of Pharmacy

References

[1] M A Fischl D D Richman N Hansen et al ldquoThe safetyand efficacy of zidovudine (AZT) in the treatment of subjectswith mildly symptomatic human immunodeficiency virus type1 (HIV) infection A double-blind placebo-controlled trialrdquoAnnals of Internal Medicine vol 112 no 10 pp 727ndash737 1990

[2] G J Veal and D J Back ldquoMetabolism of zidovudinerdquo GeneralPharmacology vol 26 no 7 pp 1469ndash1475 1995

[3] S Singh A K Dobhal A Jain J K Pandit and S ChakrabortyldquoFormulation and evaluation of solid lipid nanoparticles of awater soluble drug zidovudinerdquo Chemical and PharmaceuticalBulletin vol 58 no 5 pp 650ndash655 2010

[4] J das Neves M M Amiji M F Bahia and B SarmentoldquoNanotechnology-based systems for the treatment and preven-tion of HIVAIDSrdquo Advanced Drug Delivery Reviews vol 62no 4-5 pp 458ndash477 2010

[5] P S Kim and S W Read ldquoNanotechnology and HIV potentialapplications for treatment and preventionrdquo Wiley Interdisci-plinary Reviews vol 2 no 6 pp 693ndash702 2010

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

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CompositesJournal of

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

2 Journal of Nanotechnology

Solidification of lipid nanoemulsion is used to fabricatenanocarrier system Nowadays researchers utilize varioustechnological advances for the preparation of SLN like highshear homogenization ultrasound high pressure homoge-nization (either cold or hot homogenization) solvent emulsi-ficationevaporation and microemulsion method Materialsused in the preparation of SLNs are fatty acids triglyceridesand phospholipids SLN formulations are biocompatible withbody and more stable than liposome also provide sustaineddrug release

The sole aim of this research work was to developand assess pharmacokinetics and biodistribution of orallyadministered zidovudine-loaded SLNs (AZT-SLNs) in ratsThe main reason for the selection of peroral route of admin-istration is because IV or any other routes of administrationare not compatible with treatment involving frequent dosingPreviously several studies with the AZT were done by usingroutes of administration like duodenal and intravenous Nowthis study was focused on comparison of the pharmacoki-netics and tissue distribution of AZT-SLNs and AZT controlsolution after oral administration

2 Materials and Method

21 Materials Zidovudine was donated as a gift sample fromRanbaxy Laboratories Limited Gurgaon India Stearic acidwas purchased from CDH Delhi Tween 80 and polyvinylalcohol (PVA) were purchased from Himedia MumbaiIndia Methanol sodium acetate and glacial acetic acid wereobtained from Qualigens Navi Mumbai India Acetonitrilewas purchased from SD Fine Chem Mumbai India andheparin (Beparin 5000UmL) was from Hyderabad IndiaAll the reagents which were used for the extraction andmobile phase preparation were of HPLC grade and theremaining others were of analytical grade Deionized HPLCgrade water was prepared by Millipore system (Direct-QUV) Separated blank plasma collected from rats was kept atapproximately minus20∘C

22 Methods

221 Preparation of Zidovudine SLN AZT-SLNs were pre-pared according the procedure previously established andoptimized by Dhobal et al [3] in our nanotechnologylab Same methodology was followed for preparation ofAZT-SLNs The SLNs were prepared using wow doubleemulsion solvent evaporation method 300mg of stearicacid was dissolved in 5mL solvent mixture consisting ofdichloromethane methanol (2 3) Twenty milligrams ofAZT was dissolved in 1mL aqueous solution containing0125 vv Tween 80 Both solutions were mixed and son-icated using ultrasonicator (Hielscher Ultrasonic Processormodel number UP200H Germany) for 2min at 60∘C ampli-tude and 05 frequency The primary emulsion obtained wasthen poured into 100mL PVA solution (1 vv) at roomtemperature (25∘C) and stirred for 2 hrs at 1500 rpm SLNswere obtained as the solvent evaporates

222 Nanoparticle Size Analysis and Zeta Potential Measure-ment The zeta potential of the nanoparticles is determinedfrom the measurement of their electrophoretic mobilityand the polydispersity index is a measure of the size dis-tribution of the nanoparticle population Average particlesize polydispersity index and zeta potential of AZT-SLNswere determined in distilled water by the Delsa Nano Cparticle analyzer (Beckman Coulter USA) and the systemwas maintained at 25∘C

223 Total Drug Content (TDC) and Entrapment Efficiency(EE) Total amount of drug in formulation was measured bydissolving 1mL of SLNs formulation in 10mL of methanolThe amount of AZT in each sample was detected spec-trophotometrically (Hitachi U-1800 spectrophotometer) bymeasuring the absorbance of the clear supernatant at 120582max of265 nm ForUV absorbance placebo formulationwas treatedin the same manner as the sample and was used as blankThe given equation was used for the calculation of total drugcontent

TDC = concentration times dilution factor

times volume of formulation(1)

TheEEwas determined bymeasurement of the free drug con-tent in the supernatant obtained after centrifuging AZT-SLNsuspension in high speed cooling centrifuge at 16000 rpmfor 30min at 0∘C using Remi cooling centrifuge (MumbaiIndia) The EE was calculated as follows

EE = total drug (assay) minus free drug

total drug times 100 (2)

224 Stability Study of AZT-SLNs Prepared AZT-SLNs werelyophilized at minus30∘C under vacuum (25mbar) for 24 h ina freeze dryer (Decibel Scientific Industries ChandigarhIndia) using 1ww lactose as cryoprotectant The driedpowder was then kept in glass vials sealed with rubber capsand they were kept under ambient temperature and moisturecondition (25∘C and 60 RH) for a period of 1 2 and3 months Every month the dried powder of the stabilitysamples was redispersed in distilled water and the stability ofthe SLNs was evaluated on the basis of their particle size andthe EE of suspension

225 In Vitro Release Kinetic of AZT In vitro release studywas carried out in pH 68 phosphate buffer by using dialysisbag method using dialysis membrane having molecularweight of 12000ndash14000Da 5mL of prepared formulation wasplaced inside the dialysis bag tied at both ends and dippedin the dissolution medium which was kept at 37 plusmn 02∘Ctemperature with 100 rpm stirring speed 2mL aliquot waswithdrawn at predetermined time intervals of 025 05 1 23 4 6 8 10 12 18 and 24 hr the withdrawn amount wasreplaced by an equal volume of fresh dissolution mediumAliquots were diluted and subjected to spectrophotometricanalysis at 265 nm The unknown concentration of AZT indifferent samples was calculated from the calibration curvewhich was prepared previously

Journal of Nanotechnology 3

226 Pharmacokinetic and Tissue Distribution Study of AZT-SLNs Twelve Charles Foster strain albino rats (200ndash230 gm)of either sex aged about 3 months were selected for thepharmacokinetic study The animals for the study were kepthoused in propylene glycol cages under controlled environ-mental conditions of 25 plusmn 1∘C temperature 45ndash55 relativehumidity and 12-12 h light dark cycleThe rats had free accessto feed and water ad libitum unless otherwise stated in theexperiment Animals were acclimatized for at least one weekbefore using them for experimentsThe rats were divided intotwo groups A and B Rats from group A received 10mgkgAZT solution (1mgmL) and rats from group B received10mgkg AZT-SLN Blood was taken at predefined timeintervals before dose and 15min 30min 45min 90min 2 hr4 hr 6 hr 8 hr 10 hr and 12 hr after dose from retroorbitalplexus under slight ether anesthesia Blood was collected iniced cool heparinized eppendorf tubes Sample preparationwas done as described later All plasma sampleswere analyzedby reversed phase high performance liquid chromatography(HPLC) method The whole study was previously approvedby the Institutional Ethics Committee Institute of MedicalScience Varanasi Uttar Pradesh India

To study the tissue distribution pattern twelve rats of thesame breed of either sex were selected Rats were acclimatizedfor at least one week before using them for experimentsRats were divided into two groups A and B each grouphaving 6 rats Group A rats received 10mgkg AZT solution(1mgmL) and group B received 10mgkg dose of AZT-SLNsRats were then sacrificed by cervical dislocation at 15min30 min 45min 2 hr 4 hr and 6 hr after dosing and heartliver kidney and brain were collected after dosing Tissuesamples were washed with 09wv sterile physiologicalsaline solution and immediately weighed and stored at minus20∘Cuntil HPLC analysis

227 Sample Preparation Protein precipitation method wasused for the determination of AZT in rat plasma Thecollected blood was centrifuged at 3500 rpm (model numberC-24BL Remi Centrifuge India) for 15min at 20∘C tem-perature to separate plasma and it was stored at minus20∘Cuntil the analysis In order to ensure the effective separationof AZT from plasma components by HPLC the plasmawas deproteinized by adding 1mL acetonitrile to 100 120583L ofsample for each plasma sample which was previously spikedwith 50 120583L of AZT solution All plasma samples were thenallowed to stabilize for 30min followed by centrifugationat 15000 rpm for 15min The supernatant was transferredto a tube and evaporated to dryness at 45∘C in nitrogengas atmosphere The residue was reconstituted in 100 120583Lof mobile phase and was injected into the column for thedetection of the AZT (120582max 265 nm)

For tissue distribution study tissue samples were homog-enized in 10mL deionised water and 200 120583L of homogenatewas taken in 2mL eppendorf tube Tissue proteins wereprecipitated by adding acetonitrile up to 2mL Tissue sampleswere allowed to stabilize for 30min and centrifuged at15000 rpm for 15min The supernatant was collected and thepellete was discarded The supernatant was evaporated at

45∘C innitrogen gas streamandwas reconstituted in 100120583Lofmobile phase and injected into the column for the detectionof AZT (120582max 265 nm)

228 In Vivo Quantification of AZT A RP-HPLC system(Waters Corporation Milford MA USA) was used to quan-tify AZT in plasma HPLC (Waters 2998) was equippedwith photodiode array detector set at 265 nm and WatersSpherisorbODS2 column (250mmtimes 460mm ID 5120583mpar-ticle size) associated with guard column (46mm times 30mmID 5120583m particle size) AZT was eluted by isocratic flow at arate of 1mLmin at ambient temperature with amobile phasecomprising a mixture of acetate buffer pH 45 (135mM) andmethanol in the ratio of 75 25

229 Pharmacokinetic Analysis Pharmacokinetic analysiswas carried out by using theWinNonlin 61 Professional soft-ware (Version 53 Copyright 1998ndash2009 Pharsight corpora-tion NC USA) Noncompartmental extravascular analysismethod was employed for the pharmacokinetic parameteranalysis

2210 Statistical Analysis All pharmacokinetic parametersof AZT-SLN and AZT solution were expressed as mean plusmnstandard deviation (SD) The data were analyzed with GraphPad Prism statistical analysis using studentrsquos unpaired 119905-test119875 valueslt005lt001 and lt0001 were considered significant

3 Result

31 Characterization of AZT-SLNs The selection of a partic-ular method of encapsulation is usually determined by thesolubility characteristic of the drug As AZT is hydrophilic innature SLNs were fabricated using wow double emulsionsolvent evaporation method with appropriate modification

The particle size was observed over a range of 600ndash630 nm for the optimized AZT-SLN formulation with poly-dispersity index of 0195 The particle size distribution graphfor the optimized batch is present as Figure 1 The EE of AZTwas found to be 2706plusmn096 for this method Zeta potentialis defined as the electric charge on particle surface whichcreates an electrical barrier and acts as a ldquorepulsive factorrdquoresponsible for the stabilization of nanoparticles The zetapotential of the optimized SLN formulation was found to beminus18mV Here the observed low zeta potential was due to thenonionic nature of the surfactant (Tween 80 and PVA) SinceSLN was stored in lyophilized form zeta potential did notplay significant role in the stability of the SLN There was nosignificant change in the EE after stability studies In vitrorelease study of AZT-SLNs showed burst release followed byslow release which can be attributed to the presence of freedrug in the external phase and the absorbed drug on thesurface of the particles followed by slow release of drug fromthe encapsulated lipid matrix 60 drug was found to beavailable within 2-3 hrs of administration and this release ofdrug may be due to diffusion of drug from the pores on theparticle surface (Figure 2)

4 Journal of Nanotechnology

20

15

10

5

0

100 572 3275 18738 100000

Diameter (nm)

Diff

eren

tial i

nten

sity

()

Intensity distribution100

75

50

25

0

Cum

ulat

ive i

nten

sity

()

Figure 1 Particle size distribution graph of the optimized AZT-SLNformulation

0 4 8 12 16 20 240

102030405060708090

100

Time (hrs)

Dru

g re

leas

e (

)

Figure 2 In vitro release of the optimized AZT-SLN formulation

32 Plasma Pharmacokinetics The mean plasma concentr-ation-time profiles of the AZT-SLNs and AZT solutionare presented in Figure 3 Pharmacokinetic parameters ofAZTwere determinedusing noncompartmental analysis andthey are mentioned in Table 1 As shown at all points inFigure 3 the AZT plasma concentration was higher in ratsadministered with AZT-SLNs than those administered withAZT solution (119875 lt 005) except the first sampling pointThere was no difference in 119879max of AZT when it was givenas SLN The AUC

0ndash119905 value of AZT-SLNs was found to be 128times higher than AZT solution (119875 lt 005) At the same timethe AUC

0ndashinfin value was found to be 131 times higherThe halflife of AZT was significantly increased with AZT-SLNs (119875 lt005)The clearance rates were found to be 2312 and 2985 forAZT-SLNs and AZT solution respectively Compared withAZT solution the mean resident time (MRT) was prolongedwith AZT-SLNs (119875 lt 0001) These results demonstratedthat the incorporation of AZT into SLNs brought about anincreased absorption after oral administration

0 50 100 150 200 250 300 350 400 450 5000

1000

2000

3000

4000

5000

6000

7000

8000

AZT solutionAZT-SLNs

Time (min)

Plas

ma c

once

ntra

tion

(ng

mL)

Plasma concentration profile

Figure 3 Plasma concentration profile of AZT solution and AZT-SLNs

Table 1 Pharmacokinetic parameters for AZT solution and AZT-SLNs formulation

Parameters AZT solution(mean plusmn SD)

AZT-SLNs(mean plusmn SD)

119862max (ngmL) 646421 plusmn 1149076 399221 plusmn 2238821

119879max (min) 1500 plusmn 000 1500 plusmn 000

AUC0ndash119905

(minlowastngmL) 3143067 plusmn 703193 4035763 plusmn 4574343

AUC0ndashinfin

(minlowastngmL) 3212627 plusmn 7531474 4216763 plusmn 5296766

11990512

(min) 8041 plusmn 1215 10541 plusmn 1056

CL(mLminkg) 2985 plusmn 397 2312 plusmn 092

MRT (min) 7701 plusmn 174 14056 plusmn 1475

33 Tissue Distribution of AZT-SLNs The mean concen-tration versus time profile of each tissue for the solutionand SLNs is demonstrated in Figure 4 The 119862max in all fourcollected tissues appeared at 15min after treatment withAZT solution in rats In rats treated with AZT-SLNs the119862max appeared at the same time except in liver and brainin which 119879max was prolonged to 45min and 30min aftertreatment respectively The 119862max in brain of rats was foundto be higher after administration of AZT-SLNs as comparedto AZT solution The ratios of 119862max (AZT-SLNs to AZTsolution) in brain kidney heart and liver were 192 118 089and 075 respectively The AUC

0ndash6 h values were in the orderof kidney gt heart gt liver gt brain for the AZT solution and itwas in the order of kidney gt liver gt heart gt brain for AZT-SLNs The ratios of AZT-SLNs to AZT solution for AUC

0ndash6 hin brain liver heart and kidneywere 273 177 096 and 085

Journal of Nanotechnology 5

Liver

0 50 100 150 200 250 300 350 4000

1000

2000

3000

4000

5000

6000

7000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

AZT solutionAZT-SLNs

AZT solutionAZT-SLNs

Kidney

0 50 100 150 200 250 300 350 4000

3000

6000

9000

12000

15000

18000

21000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Heart

0 50 100 150 200 250 300 350 4000

1000

2000

3000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Brain

0 100 200 300 4000

500

1000

1500

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Figure 4 Mean concentration-time profile of various tissues

4 Discussion

Many formulations have been fabricated to improve the oralbioavailability and brain targeting of AZT Till date controlled[7] and extended [8] release matrix tablet liposomes [9ndash11]microspheres [12 13] nanocapsules [14] nanoparticles [15ndash18] nanospheres [19] thermoreversible gel [20] transdermaldrug delivery system [21] chemical drug delivery system[22] and solid lipid nanoparticle [3] have been proposed fordelivery of AZT Self-assembled drug delivery system alsohas been tried for prodrug delivery of AZT [23] Besidesperoral route various routes like intranasal intravenousand transdermal routes have been tried for targeting drugdelivery Amongst all described routes peroral route ofadministration is considered ideal because of possibility offrequent dosing and patient compliance

Targeting of antiretroviral drug to brain is importantin HIV patients because of ensuing encephalopathy on theprogression of disease AZT simply has not shown any ability

to cross the blood brain barrier The present formulationwas developed for brain targeting and increasing its thera-peutic effectiveness by modifying its pharmacokinetics Wesuccessfully prepared AZT-SLNs for oral administrationThe AUC

0ndashinfin and mean resident time (MRT) of AZT-SLNswere 127 and 183 times that AZT solution respectivelywhile Cl was decreased considerably At the same timethe 119862max of AZT-SLNs formulation was decreased whichindicates the extended release of AZT from SLNs In thepresent study decrease in Cl indicated that the excretionof AZT was delayed when incorporated into SLN Studieshave been reported that SLNs may exhibit bioadhesion tothe gastrointestinal tract wall increasing their residencetime in gastrointestinal tract In addition lipid ingredientused in the formulation of AZT-SLNs increases adhesion ofthe formulation to the intestinal epithelium and enhancespenetration of drug as compared to the solution [24]

After intragastric administration of AZT solutionthe mean peak plasma concentration of AZT was

6 Journal of Nanotechnology

646421 plusmn 114908 ngmL after oral dosing whereasin the case of AZT-SLNs observed mean peak plasmaconcentration was 399221 plusmn 22388 ngmL both appeared at119879max of 15min It was seen during study that 119862max associatedwith AZT-SLNs was less as compared to AZT solution butat the same time the AUC

0ndashinfin associated with AZT-SLNswas significantly higher than AZT solution The reasonbehind this type of kinetic behavior is because of the lipidshell surrounding the drug core which leads to the decreasein instant absorption of drug through stomach which isnot possible in case of simple solution The same is alsohelpful for explaining the extended release pattern whenformulation goes through the intestine Reportedmechanismof absorption of SLNs is mainly through Peyerrsquos patches byintracellular uptake or paracellular pathway The absorptionbehavior in this system is reported to enable bypass of gastricand intestinal degradation of the encapsulated drug and theirpossible uptake and transport through intestinal mucosa[24] It is also reported that adhesive properties due to thelipid shell increases bioavailability and reduces or minimizeserratic absorption [25 26] Despite these discussions nodata has been published so far concerning the stability ofSLNs in the GI tract The change in excretion pattern of AZTwith respect to SLNs is due to the change in distributionpattern of AZT This is due to the lymphatic absorption ofSLNs which leads to decrease in first pass metabolism ofthe drug through hepatic recirculation Significant decreasein clearance (119875 lt 001) and increase in MRT (119875 lt 0001)indicate targeting of drug directly to organs without goinginto systemic circulationThis happened due to the lymphaticabsorption of SLNs from GI tract which is supported by thetissue distribution study [27]

Higher concentrations in various tissues are essential forits pharmacological roles In the present study the ratio of119862max in the brain after administration of AZT-SLNs andAZT solution was 192 and the ratio of AUC

0ndash6 h in thebrain was 273 Based on the previous studies it is reportedthat increasing concentration of AZT in the brain is usefulfor the treatment of dementia associated with HIV uponthe intragastric administration of AZT-SLNs Under normalconditions drug penetration into the brain is restricted bythe blood brain barrier (BBB)Themechanisms for transportof SLNs through the BBB are not completely understoodThe little decrease in ratios of 119862max and AUC

0ndash6 h in heartand kidney indicated that lesser AZT was taken up in thesystemic circulation which helps in reduction of toxicityof AZT like bone marrow suppression The 119879max for AZTsolution and AZT-SLNs were 30 and 45 respectively whichindicates delayed penetration of SLNs into liver leading toincreased effectiveness of formulation by delaying first passmetabolism of drug into the liver Use of AZT-SLNs alsoresulted in decreased concentration of AZT in kidney leadingto slower excretion rate increasing the MRT It is possiblethat lipid associated with AZTmay have altered the excretionprofile because AZT itself being a water-soluble drug hasfaster excretion as compared to AZT-SLNs Graph representsthat distribution of AZT-SLN in brain was biphasic and 119879maxachieved was slower and delayed up to 30min while in caseof AZT solution it was achieved at 15min

When AZT is incorporated into nanoparticles the prop-erties of the SLNs will determine the in vivo disposition ofdrug The clearance of nanoparticles from blood circulationis done by themononuclear phagocyte system (MPS) Resultsindicate that AZT-SLNs might have been taken up in thegastrointestinal tract and translocated to the organs con-taining MPS After intragastric administration of AZT-SLNsthey were rapidly absorbed and distributed well to targettissue that is brain after a single dose administration It alsoexhibited the extended release pattern which was indicatedby its release kinetics Collectively the data indicate that SLNsare a guaranteed delivery system for the enhancement of oralabsorption of zidovudine a water-soluble drug

5 Conclusion

The present study has demonstrated that the intragastricadministration of AZT-SLNs provided prolonged drug deliv-ery and increased the AZT level in brain It can be a potentialformulation for the treatment of HIV Outcomes of this studyhave provided a basis to conduct further studies in HIVpatients

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are thankful to All India Council for TechnicalEducation (AICTE New Delhi India) for their generoussupport of this work Purvin Shah also gratefully acknowl-edges the financial assistance provided by University GrantCommission (UGC New Delhi India) in the form of JuniorResearch Fellowship for the partial fulfillment of the require-ments for the degree of Master of Pharmacy

References

[1] M A Fischl D D Richman N Hansen et al ldquoThe safetyand efficacy of zidovudine (AZT) in the treatment of subjectswith mildly symptomatic human immunodeficiency virus type1 (HIV) infection A double-blind placebo-controlled trialrdquoAnnals of Internal Medicine vol 112 no 10 pp 727ndash737 1990

[2] G J Veal and D J Back ldquoMetabolism of zidovudinerdquo GeneralPharmacology vol 26 no 7 pp 1469ndash1475 1995

[3] S Singh A K Dobhal A Jain J K Pandit and S ChakrabortyldquoFormulation and evaluation of solid lipid nanoparticles of awater soluble drug zidovudinerdquo Chemical and PharmaceuticalBulletin vol 58 no 5 pp 650ndash655 2010

[4] J das Neves M M Amiji M F Bahia and B SarmentoldquoNanotechnology-based systems for the treatment and preven-tion of HIVAIDSrdquo Advanced Drug Delivery Reviews vol 62no 4-5 pp 458ndash477 2010

[5] P S Kim and S W Read ldquoNanotechnology and HIV potentialapplications for treatment and preventionrdquo Wiley Interdisci-plinary Reviews vol 2 no 6 pp 693ndash702 2010

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

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ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanotechnology 3

226 Pharmacokinetic and Tissue Distribution Study of AZT-SLNs Twelve Charles Foster strain albino rats (200ndash230 gm)of either sex aged about 3 months were selected for thepharmacokinetic study The animals for the study were kepthoused in propylene glycol cages under controlled environ-mental conditions of 25 plusmn 1∘C temperature 45ndash55 relativehumidity and 12-12 h light dark cycleThe rats had free accessto feed and water ad libitum unless otherwise stated in theexperiment Animals were acclimatized for at least one weekbefore using them for experimentsThe rats were divided intotwo groups A and B Rats from group A received 10mgkgAZT solution (1mgmL) and rats from group B received10mgkg AZT-SLN Blood was taken at predefined timeintervals before dose and 15min 30min 45min 90min 2 hr4 hr 6 hr 8 hr 10 hr and 12 hr after dose from retroorbitalplexus under slight ether anesthesia Blood was collected iniced cool heparinized eppendorf tubes Sample preparationwas done as described later All plasma sampleswere analyzedby reversed phase high performance liquid chromatography(HPLC) method The whole study was previously approvedby the Institutional Ethics Committee Institute of MedicalScience Varanasi Uttar Pradesh India

To study the tissue distribution pattern twelve rats of thesame breed of either sex were selected Rats were acclimatizedfor at least one week before using them for experimentsRats were divided into two groups A and B each grouphaving 6 rats Group A rats received 10mgkg AZT solution(1mgmL) and group B received 10mgkg dose of AZT-SLNsRats were then sacrificed by cervical dislocation at 15min30 min 45min 2 hr 4 hr and 6 hr after dosing and heartliver kidney and brain were collected after dosing Tissuesamples were washed with 09wv sterile physiologicalsaline solution and immediately weighed and stored at minus20∘Cuntil HPLC analysis

227 Sample Preparation Protein precipitation method wasused for the determination of AZT in rat plasma Thecollected blood was centrifuged at 3500 rpm (model numberC-24BL Remi Centrifuge India) for 15min at 20∘C tem-perature to separate plasma and it was stored at minus20∘Cuntil the analysis In order to ensure the effective separationof AZT from plasma components by HPLC the plasmawas deproteinized by adding 1mL acetonitrile to 100 120583L ofsample for each plasma sample which was previously spikedwith 50 120583L of AZT solution All plasma samples were thenallowed to stabilize for 30min followed by centrifugationat 15000 rpm for 15min The supernatant was transferredto a tube and evaporated to dryness at 45∘C in nitrogengas atmosphere The residue was reconstituted in 100 120583Lof mobile phase and was injected into the column for thedetection of the AZT (120582max 265 nm)

For tissue distribution study tissue samples were homog-enized in 10mL deionised water and 200 120583L of homogenatewas taken in 2mL eppendorf tube Tissue proteins wereprecipitated by adding acetonitrile up to 2mL Tissue sampleswere allowed to stabilize for 30min and centrifuged at15000 rpm for 15min The supernatant was collected and thepellete was discarded The supernatant was evaporated at

45∘C innitrogen gas streamandwas reconstituted in 100120583Lofmobile phase and injected into the column for the detectionof AZT (120582max 265 nm)

228 In Vivo Quantification of AZT A RP-HPLC system(Waters Corporation Milford MA USA) was used to quan-tify AZT in plasma HPLC (Waters 2998) was equippedwith photodiode array detector set at 265 nm and WatersSpherisorbODS2 column (250mmtimes 460mm ID 5120583mpar-ticle size) associated with guard column (46mm times 30mmID 5120583m particle size) AZT was eluted by isocratic flow at arate of 1mLmin at ambient temperature with amobile phasecomprising a mixture of acetate buffer pH 45 (135mM) andmethanol in the ratio of 75 25

229 Pharmacokinetic Analysis Pharmacokinetic analysiswas carried out by using theWinNonlin 61 Professional soft-ware (Version 53 Copyright 1998ndash2009 Pharsight corpora-tion NC USA) Noncompartmental extravascular analysismethod was employed for the pharmacokinetic parameteranalysis

2210 Statistical Analysis All pharmacokinetic parametersof AZT-SLN and AZT solution were expressed as mean plusmnstandard deviation (SD) The data were analyzed with GraphPad Prism statistical analysis using studentrsquos unpaired 119905-test119875 valueslt005lt001 and lt0001 were considered significant

3 Result

31 Characterization of AZT-SLNs The selection of a partic-ular method of encapsulation is usually determined by thesolubility characteristic of the drug As AZT is hydrophilic innature SLNs were fabricated using wow double emulsionsolvent evaporation method with appropriate modification

The particle size was observed over a range of 600ndash630 nm for the optimized AZT-SLN formulation with poly-dispersity index of 0195 The particle size distribution graphfor the optimized batch is present as Figure 1 The EE of AZTwas found to be 2706plusmn096 for this method Zeta potentialis defined as the electric charge on particle surface whichcreates an electrical barrier and acts as a ldquorepulsive factorrdquoresponsible for the stabilization of nanoparticles The zetapotential of the optimized SLN formulation was found to beminus18mV Here the observed low zeta potential was due to thenonionic nature of the surfactant (Tween 80 and PVA) SinceSLN was stored in lyophilized form zeta potential did notplay significant role in the stability of the SLN There was nosignificant change in the EE after stability studies In vitrorelease study of AZT-SLNs showed burst release followed byslow release which can be attributed to the presence of freedrug in the external phase and the absorbed drug on thesurface of the particles followed by slow release of drug fromthe encapsulated lipid matrix 60 drug was found to beavailable within 2-3 hrs of administration and this release ofdrug may be due to diffusion of drug from the pores on theparticle surface (Figure 2)

4 Journal of Nanotechnology

20

15

10

5

0

100 572 3275 18738 100000

Diameter (nm)

Diff

eren

tial i

nten

sity

()

Intensity distribution100

75

50

25

0

Cum

ulat

ive i

nten

sity

()

Figure 1 Particle size distribution graph of the optimized AZT-SLNformulation

0 4 8 12 16 20 240

102030405060708090

100

Time (hrs)

Dru

g re

leas

e (

)

Figure 2 In vitro release of the optimized AZT-SLN formulation

32 Plasma Pharmacokinetics The mean plasma concentr-ation-time profiles of the AZT-SLNs and AZT solutionare presented in Figure 3 Pharmacokinetic parameters ofAZTwere determinedusing noncompartmental analysis andthey are mentioned in Table 1 As shown at all points inFigure 3 the AZT plasma concentration was higher in ratsadministered with AZT-SLNs than those administered withAZT solution (119875 lt 005) except the first sampling pointThere was no difference in 119879max of AZT when it was givenas SLN The AUC

0ndash119905 value of AZT-SLNs was found to be 128times higher than AZT solution (119875 lt 005) At the same timethe AUC

0ndashinfin value was found to be 131 times higherThe halflife of AZT was significantly increased with AZT-SLNs (119875 lt005)The clearance rates were found to be 2312 and 2985 forAZT-SLNs and AZT solution respectively Compared withAZT solution the mean resident time (MRT) was prolongedwith AZT-SLNs (119875 lt 0001) These results demonstratedthat the incorporation of AZT into SLNs brought about anincreased absorption after oral administration

0 50 100 150 200 250 300 350 400 450 5000

1000

2000

3000

4000

5000

6000

7000

8000

AZT solutionAZT-SLNs

Time (min)

Plas

ma c

once

ntra

tion

(ng

mL)

Plasma concentration profile

Figure 3 Plasma concentration profile of AZT solution and AZT-SLNs

Table 1 Pharmacokinetic parameters for AZT solution and AZT-SLNs formulation

Parameters AZT solution(mean plusmn SD)

AZT-SLNs(mean plusmn SD)

119862max (ngmL) 646421 plusmn 1149076 399221 plusmn 2238821

119879max (min) 1500 plusmn 000 1500 plusmn 000

AUC0ndash119905

(minlowastngmL) 3143067 plusmn 703193 4035763 plusmn 4574343

AUC0ndashinfin

(minlowastngmL) 3212627 plusmn 7531474 4216763 plusmn 5296766

11990512

(min) 8041 plusmn 1215 10541 plusmn 1056

CL(mLminkg) 2985 plusmn 397 2312 plusmn 092

MRT (min) 7701 plusmn 174 14056 plusmn 1475

33 Tissue Distribution of AZT-SLNs The mean concen-tration versus time profile of each tissue for the solutionand SLNs is demonstrated in Figure 4 The 119862max in all fourcollected tissues appeared at 15min after treatment withAZT solution in rats In rats treated with AZT-SLNs the119862max appeared at the same time except in liver and brainin which 119879max was prolonged to 45min and 30min aftertreatment respectively The 119862max in brain of rats was foundto be higher after administration of AZT-SLNs as comparedto AZT solution The ratios of 119862max (AZT-SLNs to AZTsolution) in brain kidney heart and liver were 192 118 089and 075 respectively The AUC

0ndash6 h values were in the orderof kidney gt heart gt liver gt brain for the AZT solution and itwas in the order of kidney gt liver gt heart gt brain for AZT-SLNs The ratios of AZT-SLNs to AZT solution for AUC

0ndash6 hin brain liver heart and kidneywere 273 177 096 and 085

Journal of Nanotechnology 5

Liver

0 50 100 150 200 250 300 350 4000

1000

2000

3000

4000

5000

6000

7000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

AZT solutionAZT-SLNs

AZT solutionAZT-SLNs

Kidney

0 50 100 150 200 250 300 350 4000

3000

6000

9000

12000

15000

18000

21000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Heart

0 50 100 150 200 250 300 350 4000

1000

2000

3000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Brain

0 100 200 300 4000

500

1000

1500

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Figure 4 Mean concentration-time profile of various tissues

4 Discussion

Many formulations have been fabricated to improve the oralbioavailability and brain targeting of AZT Till date controlled[7] and extended [8] release matrix tablet liposomes [9ndash11]microspheres [12 13] nanocapsules [14] nanoparticles [15ndash18] nanospheres [19] thermoreversible gel [20] transdermaldrug delivery system [21] chemical drug delivery system[22] and solid lipid nanoparticle [3] have been proposed fordelivery of AZT Self-assembled drug delivery system alsohas been tried for prodrug delivery of AZT [23] Besidesperoral route various routes like intranasal intravenousand transdermal routes have been tried for targeting drugdelivery Amongst all described routes peroral route ofadministration is considered ideal because of possibility offrequent dosing and patient compliance

Targeting of antiretroviral drug to brain is importantin HIV patients because of ensuing encephalopathy on theprogression of disease AZT simply has not shown any ability

to cross the blood brain barrier The present formulationwas developed for brain targeting and increasing its thera-peutic effectiveness by modifying its pharmacokinetics Wesuccessfully prepared AZT-SLNs for oral administrationThe AUC

0ndashinfin and mean resident time (MRT) of AZT-SLNswere 127 and 183 times that AZT solution respectivelywhile Cl was decreased considerably At the same timethe 119862max of AZT-SLNs formulation was decreased whichindicates the extended release of AZT from SLNs In thepresent study decrease in Cl indicated that the excretionof AZT was delayed when incorporated into SLN Studieshave been reported that SLNs may exhibit bioadhesion tothe gastrointestinal tract wall increasing their residencetime in gastrointestinal tract In addition lipid ingredientused in the formulation of AZT-SLNs increases adhesion ofthe formulation to the intestinal epithelium and enhancespenetration of drug as compared to the solution [24]

After intragastric administration of AZT solutionthe mean peak plasma concentration of AZT was

6 Journal of Nanotechnology

646421 plusmn 114908 ngmL after oral dosing whereasin the case of AZT-SLNs observed mean peak plasmaconcentration was 399221 plusmn 22388 ngmL both appeared at119879max of 15min It was seen during study that 119862max associatedwith AZT-SLNs was less as compared to AZT solution butat the same time the AUC

0ndashinfin associated with AZT-SLNswas significantly higher than AZT solution The reasonbehind this type of kinetic behavior is because of the lipidshell surrounding the drug core which leads to the decreasein instant absorption of drug through stomach which isnot possible in case of simple solution The same is alsohelpful for explaining the extended release pattern whenformulation goes through the intestine Reportedmechanismof absorption of SLNs is mainly through Peyerrsquos patches byintracellular uptake or paracellular pathway The absorptionbehavior in this system is reported to enable bypass of gastricand intestinal degradation of the encapsulated drug and theirpossible uptake and transport through intestinal mucosa[24] It is also reported that adhesive properties due to thelipid shell increases bioavailability and reduces or minimizeserratic absorption [25 26] Despite these discussions nodata has been published so far concerning the stability ofSLNs in the GI tract The change in excretion pattern of AZTwith respect to SLNs is due to the change in distributionpattern of AZT This is due to the lymphatic absorption ofSLNs which leads to decrease in first pass metabolism ofthe drug through hepatic recirculation Significant decreasein clearance (119875 lt 001) and increase in MRT (119875 lt 0001)indicate targeting of drug directly to organs without goinginto systemic circulationThis happened due to the lymphaticabsorption of SLNs from GI tract which is supported by thetissue distribution study [27]

Higher concentrations in various tissues are essential forits pharmacological roles In the present study the ratio of119862max in the brain after administration of AZT-SLNs andAZT solution was 192 and the ratio of AUC

0ndash6 h in thebrain was 273 Based on the previous studies it is reportedthat increasing concentration of AZT in the brain is usefulfor the treatment of dementia associated with HIV uponthe intragastric administration of AZT-SLNs Under normalconditions drug penetration into the brain is restricted bythe blood brain barrier (BBB)Themechanisms for transportof SLNs through the BBB are not completely understoodThe little decrease in ratios of 119862max and AUC

0ndash6 h in heartand kidney indicated that lesser AZT was taken up in thesystemic circulation which helps in reduction of toxicityof AZT like bone marrow suppression The 119879max for AZTsolution and AZT-SLNs were 30 and 45 respectively whichindicates delayed penetration of SLNs into liver leading toincreased effectiveness of formulation by delaying first passmetabolism of drug into the liver Use of AZT-SLNs alsoresulted in decreased concentration of AZT in kidney leadingto slower excretion rate increasing the MRT It is possiblethat lipid associated with AZTmay have altered the excretionprofile because AZT itself being a water-soluble drug hasfaster excretion as compared to AZT-SLNs Graph representsthat distribution of AZT-SLN in brain was biphasic and 119879maxachieved was slower and delayed up to 30min while in caseof AZT solution it was achieved at 15min

When AZT is incorporated into nanoparticles the prop-erties of the SLNs will determine the in vivo disposition ofdrug The clearance of nanoparticles from blood circulationis done by themononuclear phagocyte system (MPS) Resultsindicate that AZT-SLNs might have been taken up in thegastrointestinal tract and translocated to the organs con-taining MPS After intragastric administration of AZT-SLNsthey were rapidly absorbed and distributed well to targettissue that is brain after a single dose administration It alsoexhibited the extended release pattern which was indicatedby its release kinetics Collectively the data indicate that SLNsare a guaranteed delivery system for the enhancement of oralabsorption of zidovudine a water-soluble drug

5 Conclusion

The present study has demonstrated that the intragastricadministration of AZT-SLNs provided prolonged drug deliv-ery and increased the AZT level in brain It can be a potentialformulation for the treatment of HIV Outcomes of this studyhave provided a basis to conduct further studies in HIVpatients

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are thankful to All India Council for TechnicalEducation (AICTE New Delhi India) for their generoussupport of this work Purvin Shah also gratefully acknowl-edges the financial assistance provided by University GrantCommission (UGC New Delhi India) in the form of JuniorResearch Fellowship for the partial fulfillment of the require-ments for the degree of Master of Pharmacy

References

[1] M A Fischl D D Richman N Hansen et al ldquoThe safetyand efficacy of zidovudine (AZT) in the treatment of subjectswith mildly symptomatic human immunodeficiency virus type1 (HIV) infection A double-blind placebo-controlled trialrdquoAnnals of Internal Medicine vol 112 no 10 pp 727ndash737 1990

[2] G J Veal and D J Back ldquoMetabolism of zidovudinerdquo GeneralPharmacology vol 26 no 7 pp 1469ndash1475 1995

[3] S Singh A K Dobhal A Jain J K Pandit and S ChakrabortyldquoFormulation and evaluation of solid lipid nanoparticles of awater soluble drug zidovudinerdquo Chemical and PharmaceuticalBulletin vol 58 no 5 pp 650ndash655 2010

[4] J das Neves M M Amiji M F Bahia and B SarmentoldquoNanotechnology-based systems for the treatment and preven-tion of HIVAIDSrdquo Advanced Drug Delivery Reviews vol 62no 4-5 pp 458ndash477 2010

[5] P S Kim and S W Read ldquoNanotechnology and HIV potentialapplications for treatment and preventionrdquo Wiley Interdisci-plinary Reviews vol 2 no 6 pp 693ndash702 2010

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

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TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

4 Journal of Nanotechnology

20

15

10

5

0

100 572 3275 18738 100000

Diameter (nm)

Diff

eren

tial i

nten

sity

()

Intensity distribution100

75

50

25

0

Cum

ulat

ive i

nten

sity

()

Figure 1 Particle size distribution graph of the optimized AZT-SLNformulation

0 4 8 12 16 20 240

102030405060708090

100

Time (hrs)

Dru

g re

leas

e (

)

Figure 2 In vitro release of the optimized AZT-SLN formulation

32 Plasma Pharmacokinetics The mean plasma concentr-ation-time profiles of the AZT-SLNs and AZT solutionare presented in Figure 3 Pharmacokinetic parameters ofAZTwere determinedusing noncompartmental analysis andthey are mentioned in Table 1 As shown at all points inFigure 3 the AZT plasma concentration was higher in ratsadministered with AZT-SLNs than those administered withAZT solution (119875 lt 005) except the first sampling pointThere was no difference in 119879max of AZT when it was givenas SLN The AUC

0ndash119905 value of AZT-SLNs was found to be 128times higher than AZT solution (119875 lt 005) At the same timethe AUC

0ndashinfin value was found to be 131 times higherThe halflife of AZT was significantly increased with AZT-SLNs (119875 lt005)The clearance rates were found to be 2312 and 2985 forAZT-SLNs and AZT solution respectively Compared withAZT solution the mean resident time (MRT) was prolongedwith AZT-SLNs (119875 lt 0001) These results demonstratedthat the incorporation of AZT into SLNs brought about anincreased absorption after oral administration

0 50 100 150 200 250 300 350 400 450 5000

1000

2000

3000

4000

5000

6000

7000

8000

AZT solutionAZT-SLNs

Time (min)

Plas

ma c

once

ntra

tion

(ng

mL)

Plasma concentration profile

Figure 3 Plasma concentration profile of AZT solution and AZT-SLNs

Table 1 Pharmacokinetic parameters for AZT solution and AZT-SLNs formulation

Parameters AZT solution(mean plusmn SD)

AZT-SLNs(mean plusmn SD)

119862max (ngmL) 646421 plusmn 1149076 399221 plusmn 2238821

119879max (min) 1500 plusmn 000 1500 plusmn 000

AUC0ndash119905

(minlowastngmL) 3143067 plusmn 703193 4035763 plusmn 4574343

AUC0ndashinfin

(minlowastngmL) 3212627 plusmn 7531474 4216763 plusmn 5296766

11990512

(min) 8041 plusmn 1215 10541 plusmn 1056

CL(mLminkg) 2985 plusmn 397 2312 plusmn 092

MRT (min) 7701 plusmn 174 14056 plusmn 1475

33 Tissue Distribution of AZT-SLNs The mean concen-tration versus time profile of each tissue for the solutionand SLNs is demonstrated in Figure 4 The 119862max in all fourcollected tissues appeared at 15min after treatment withAZT solution in rats In rats treated with AZT-SLNs the119862max appeared at the same time except in liver and brainin which 119879max was prolonged to 45min and 30min aftertreatment respectively The 119862max in brain of rats was foundto be higher after administration of AZT-SLNs as comparedto AZT solution The ratios of 119862max (AZT-SLNs to AZTsolution) in brain kidney heart and liver were 192 118 089and 075 respectively The AUC

0ndash6 h values were in the orderof kidney gt heart gt liver gt brain for the AZT solution and itwas in the order of kidney gt liver gt heart gt brain for AZT-SLNs The ratios of AZT-SLNs to AZT solution for AUC

0ndash6 hin brain liver heart and kidneywere 273 177 096 and 085

Journal of Nanotechnology 5

Liver

0 50 100 150 200 250 300 350 4000

1000

2000

3000

4000

5000

6000

7000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

AZT solutionAZT-SLNs

AZT solutionAZT-SLNs

Kidney

0 50 100 150 200 250 300 350 4000

3000

6000

9000

12000

15000

18000

21000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Heart

0 50 100 150 200 250 300 350 4000

1000

2000

3000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Brain

0 100 200 300 4000

500

1000

1500

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Figure 4 Mean concentration-time profile of various tissues

4 Discussion

Many formulations have been fabricated to improve the oralbioavailability and brain targeting of AZT Till date controlled[7] and extended [8] release matrix tablet liposomes [9ndash11]microspheres [12 13] nanocapsules [14] nanoparticles [15ndash18] nanospheres [19] thermoreversible gel [20] transdermaldrug delivery system [21] chemical drug delivery system[22] and solid lipid nanoparticle [3] have been proposed fordelivery of AZT Self-assembled drug delivery system alsohas been tried for prodrug delivery of AZT [23] Besidesperoral route various routes like intranasal intravenousand transdermal routes have been tried for targeting drugdelivery Amongst all described routes peroral route ofadministration is considered ideal because of possibility offrequent dosing and patient compliance

Targeting of antiretroviral drug to brain is importantin HIV patients because of ensuing encephalopathy on theprogression of disease AZT simply has not shown any ability

to cross the blood brain barrier The present formulationwas developed for brain targeting and increasing its thera-peutic effectiveness by modifying its pharmacokinetics Wesuccessfully prepared AZT-SLNs for oral administrationThe AUC

0ndashinfin and mean resident time (MRT) of AZT-SLNswere 127 and 183 times that AZT solution respectivelywhile Cl was decreased considerably At the same timethe 119862max of AZT-SLNs formulation was decreased whichindicates the extended release of AZT from SLNs In thepresent study decrease in Cl indicated that the excretionof AZT was delayed when incorporated into SLN Studieshave been reported that SLNs may exhibit bioadhesion tothe gastrointestinal tract wall increasing their residencetime in gastrointestinal tract In addition lipid ingredientused in the formulation of AZT-SLNs increases adhesion ofthe formulation to the intestinal epithelium and enhancespenetration of drug as compared to the solution [24]

After intragastric administration of AZT solutionthe mean peak plasma concentration of AZT was

6 Journal of Nanotechnology

646421 plusmn 114908 ngmL after oral dosing whereasin the case of AZT-SLNs observed mean peak plasmaconcentration was 399221 plusmn 22388 ngmL both appeared at119879max of 15min It was seen during study that 119862max associatedwith AZT-SLNs was less as compared to AZT solution butat the same time the AUC

0ndashinfin associated with AZT-SLNswas significantly higher than AZT solution The reasonbehind this type of kinetic behavior is because of the lipidshell surrounding the drug core which leads to the decreasein instant absorption of drug through stomach which isnot possible in case of simple solution The same is alsohelpful for explaining the extended release pattern whenformulation goes through the intestine Reportedmechanismof absorption of SLNs is mainly through Peyerrsquos patches byintracellular uptake or paracellular pathway The absorptionbehavior in this system is reported to enable bypass of gastricand intestinal degradation of the encapsulated drug and theirpossible uptake and transport through intestinal mucosa[24] It is also reported that adhesive properties due to thelipid shell increases bioavailability and reduces or minimizeserratic absorption [25 26] Despite these discussions nodata has been published so far concerning the stability ofSLNs in the GI tract The change in excretion pattern of AZTwith respect to SLNs is due to the change in distributionpattern of AZT This is due to the lymphatic absorption ofSLNs which leads to decrease in first pass metabolism ofthe drug through hepatic recirculation Significant decreasein clearance (119875 lt 001) and increase in MRT (119875 lt 0001)indicate targeting of drug directly to organs without goinginto systemic circulationThis happened due to the lymphaticabsorption of SLNs from GI tract which is supported by thetissue distribution study [27]

Higher concentrations in various tissues are essential forits pharmacological roles In the present study the ratio of119862max in the brain after administration of AZT-SLNs andAZT solution was 192 and the ratio of AUC

0ndash6 h in thebrain was 273 Based on the previous studies it is reportedthat increasing concentration of AZT in the brain is usefulfor the treatment of dementia associated with HIV uponthe intragastric administration of AZT-SLNs Under normalconditions drug penetration into the brain is restricted bythe blood brain barrier (BBB)Themechanisms for transportof SLNs through the BBB are not completely understoodThe little decrease in ratios of 119862max and AUC

0ndash6 h in heartand kidney indicated that lesser AZT was taken up in thesystemic circulation which helps in reduction of toxicityof AZT like bone marrow suppression The 119879max for AZTsolution and AZT-SLNs were 30 and 45 respectively whichindicates delayed penetration of SLNs into liver leading toincreased effectiveness of formulation by delaying first passmetabolism of drug into the liver Use of AZT-SLNs alsoresulted in decreased concentration of AZT in kidney leadingto slower excretion rate increasing the MRT It is possiblethat lipid associated with AZTmay have altered the excretionprofile because AZT itself being a water-soluble drug hasfaster excretion as compared to AZT-SLNs Graph representsthat distribution of AZT-SLN in brain was biphasic and 119879maxachieved was slower and delayed up to 30min while in caseof AZT solution it was achieved at 15min

When AZT is incorporated into nanoparticles the prop-erties of the SLNs will determine the in vivo disposition ofdrug The clearance of nanoparticles from blood circulationis done by themononuclear phagocyte system (MPS) Resultsindicate that AZT-SLNs might have been taken up in thegastrointestinal tract and translocated to the organs con-taining MPS After intragastric administration of AZT-SLNsthey were rapidly absorbed and distributed well to targettissue that is brain after a single dose administration It alsoexhibited the extended release pattern which was indicatedby its release kinetics Collectively the data indicate that SLNsare a guaranteed delivery system for the enhancement of oralabsorption of zidovudine a water-soluble drug

5 Conclusion

The present study has demonstrated that the intragastricadministration of AZT-SLNs provided prolonged drug deliv-ery and increased the AZT level in brain It can be a potentialformulation for the treatment of HIV Outcomes of this studyhave provided a basis to conduct further studies in HIVpatients

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are thankful to All India Council for TechnicalEducation (AICTE New Delhi India) for their generoussupport of this work Purvin Shah also gratefully acknowl-edges the financial assistance provided by University GrantCommission (UGC New Delhi India) in the form of JuniorResearch Fellowship for the partial fulfillment of the require-ments for the degree of Master of Pharmacy

References

[1] M A Fischl D D Richman N Hansen et al ldquoThe safetyand efficacy of zidovudine (AZT) in the treatment of subjectswith mildly symptomatic human immunodeficiency virus type1 (HIV) infection A double-blind placebo-controlled trialrdquoAnnals of Internal Medicine vol 112 no 10 pp 727ndash737 1990

[2] G J Veal and D J Back ldquoMetabolism of zidovudinerdquo GeneralPharmacology vol 26 no 7 pp 1469ndash1475 1995

[3] S Singh A K Dobhal A Jain J K Pandit and S ChakrabortyldquoFormulation and evaluation of solid lipid nanoparticles of awater soluble drug zidovudinerdquo Chemical and PharmaceuticalBulletin vol 58 no 5 pp 650ndash655 2010

[4] J das Neves M M Amiji M F Bahia and B SarmentoldquoNanotechnology-based systems for the treatment and preven-tion of HIVAIDSrdquo Advanced Drug Delivery Reviews vol 62no 4-5 pp 458ndash477 2010

[5] P S Kim and S W Read ldquoNanotechnology and HIV potentialapplications for treatment and preventionrdquo Wiley Interdisci-plinary Reviews vol 2 no 6 pp 693ndash702 2010

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanotechnology 5

Liver

0 50 100 150 200 250 300 350 4000

1000

2000

3000

4000

5000

6000

7000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

AZT solutionAZT-SLNs

AZT solutionAZT-SLNs

Kidney

0 50 100 150 200 250 300 350 4000

3000

6000

9000

12000

15000

18000

21000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Heart

0 50 100 150 200 250 300 350 4000

1000

2000

3000

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Brain

0 100 200 300 4000

500

1000

1500

Time (min)

Plas

ma c

once

ntra

tion

(ng

g)

Figure 4 Mean concentration-time profile of various tissues

4 Discussion

Many formulations have been fabricated to improve the oralbioavailability and brain targeting of AZT Till date controlled[7] and extended [8] release matrix tablet liposomes [9ndash11]microspheres [12 13] nanocapsules [14] nanoparticles [15ndash18] nanospheres [19] thermoreversible gel [20] transdermaldrug delivery system [21] chemical drug delivery system[22] and solid lipid nanoparticle [3] have been proposed fordelivery of AZT Self-assembled drug delivery system alsohas been tried for prodrug delivery of AZT [23] Besidesperoral route various routes like intranasal intravenousand transdermal routes have been tried for targeting drugdelivery Amongst all described routes peroral route ofadministration is considered ideal because of possibility offrequent dosing and patient compliance

Targeting of antiretroviral drug to brain is importantin HIV patients because of ensuing encephalopathy on theprogression of disease AZT simply has not shown any ability

to cross the blood brain barrier The present formulationwas developed for brain targeting and increasing its thera-peutic effectiveness by modifying its pharmacokinetics Wesuccessfully prepared AZT-SLNs for oral administrationThe AUC

0ndashinfin and mean resident time (MRT) of AZT-SLNswere 127 and 183 times that AZT solution respectivelywhile Cl was decreased considerably At the same timethe 119862max of AZT-SLNs formulation was decreased whichindicates the extended release of AZT from SLNs In thepresent study decrease in Cl indicated that the excretionof AZT was delayed when incorporated into SLN Studieshave been reported that SLNs may exhibit bioadhesion tothe gastrointestinal tract wall increasing their residencetime in gastrointestinal tract In addition lipid ingredientused in the formulation of AZT-SLNs increases adhesion ofthe formulation to the intestinal epithelium and enhancespenetration of drug as compared to the solution [24]

After intragastric administration of AZT solutionthe mean peak plasma concentration of AZT was

6 Journal of Nanotechnology

646421 plusmn 114908 ngmL after oral dosing whereasin the case of AZT-SLNs observed mean peak plasmaconcentration was 399221 plusmn 22388 ngmL both appeared at119879max of 15min It was seen during study that 119862max associatedwith AZT-SLNs was less as compared to AZT solution butat the same time the AUC

0ndashinfin associated with AZT-SLNswas significantly higher than AZT solution The reasonbehind this type of kinetic behavior is because of the lipidshell surrounding the drug core which leads to the decreasein instant absorption of drug through stomach which isnot possible in case of simple solution The same is alsohelpful for explaining the extended release pattern whenformulation goes through the intestine Reportedmechanismof absorption of SLNs is mainly through Peyerrsquos patches byintracellular uptake or paracellular pathway The absorptionbehavior in this system is reported to enable bypass of gastricand intestinal degradation of the encapsulated drug and theirpossible uptake and transport through intestinal mucosa[24] It is also reported that adhesive properties due to thelipid shell increases bioavailability and reduces or minimizeserratic absorption [25 26] Despite these discussions nodata has been published so far concerning the stability ofSLNs in the GI tract The change in excretion pattern of AZTwith respect to SLNs is due to the change in distributionpattern of AZT This is due to the lymphatic absorption ofSLNs which leads to decrease in first pass metabolism ofthe drug through hepatic recirculation Significant decreasein clearance (119875 lt 001) and increase in MRT (119875 lt 0001)indicate targeting of drug directly to organs without goinginto systemic circulationThis happened due to the lymphaticabsorption of SLNs from GI tract which is supported by thetissue distribution study [27]

Higher concentrations in various tissues are essential forits pharmacological roles In the present study the ratio of119862max in the brain after administration of AZT-SLNs andAZT solution was 192 and the ratio of AUC

0ndash6 h in thebrain was 273 Based on the previous studies it is reportedthat increasing concentration of AZT in the brain is usefulfor the treatment of dementia associated with HIV uponthe intragastric administration of AZT-SLNs Under normalconditions drug penetration into the brain is restricted bythe blood brain barrier (BBB)Themechanisms for transportof SLNs through the BBB are not completely understoodThe little decrease in ratios of 119862max and AUC

0ndash6 h in heartand kidney indicated that lesser AZT was taken up in thesystemic circulation which helps in reduction of toxicityof AZT like bone marrow suppression The 119879max for AZTsolution and AZT-SLNs were 30 and 45 respectively whichindicates delayed penetration of SLNs into liver leading toincreased effectiveness of formulation by delaying first passmetabolism of drug into the liver Use of AZT-SLNs alsoresulted in decreased concentration of AZT in kidney leadingto slower excretion rate increasing the MRT It is possiblethat lipid associated with AZTmay have altered the excretionprofile because AZT itself being a water-soluble drug hasfaster excretion as compared to AZT-SLNs Graph representsthat distribution of AZT-SLN in brain was biphasic and 119879maxachieved was slower and delayed up to 30min while in caseof AZT solution it was achieved at 15min

When AZT is incorporated into nanoparticles the prop-erties of the SLNs will determine the in vivo disposition ofdrug The clearance of nanoparticles from blood circulationis done by themononuclear phagocyte system (MPS) Resultsindicate that AZT-SLNs might have been taken up in thegastrointestinal tract and translocated to the organs con-taining MPS After intragastric administration of AZT-SLNsthey were rapidly absorbed and distributed well to targettissue that is brain after a single dose administration It alsoexhibited the extended release pattern which was indicatedby its release kinetics Collectively the data indicate that SLNsare a guaranteed delivery system for the enhancement of oralabsorption of zidovudine a water-soluble drug

5 Conclusion

The present study has demonstrated that the intragastricadministration of AZT-SLNs provided prolonged drug deliv-ery and increased the AZT level in brain It can be a potentialformulation for the treatment of HIV Outcomes of this studyhave provided a basis to conduct further studies in HIVpatients

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are thankful to All India Council for TechnicalEducation (AICTE New Delhi India) for their generoussupport of this work Purvin Shah also gratefully acknowl-edges the financial assistance provided by University GrantCommission (UGC New Delhi India) in the form of JuniorResearch Fellowship for the partial fulfillment of the require-ments for the degree of Master of Pharmacy

References

[1] M A Fischl D D Richman N Hansen et al ldquoThe safetyand efficacy of zidovudine (AZT) in the treatment of subjectswith mildly symptomatic human immunodeficiency virus type1 (HIV) infection A double-blind placebo-controlled trialrdquoAnnals of Internal Medicine vol 112 no 10 pp 727ndash737 1990

[2] G J Veal and D J Back ldquoMetabolism of zidovudinerdquo GeneralPharmacology vol 26 no 7 pp 1469ndash1475 1995

[3] S Singh A K Dobhal A Jain J K Pandit and S ChakrabortyldquoFormulation and evaluation of solid lipid nanoparticles of awater soluble drug zidovudinerdquo Chemical and PharmaceuticalBulletin vol 58 no 5 pp 650ndash655 2010

[4] J das Neves M M Amiji M F Bahia and B SarmentoldquoNanotechnology-based systems for the treatment and preven-tion of HIVAIDSrdquo Advanced Drug Delivery Reviews vol 62no 4-5 pp 458ndash477 2010

[5] P S Kim and S W Read ldquoNanotechnology and HIV potentialapplications for treatment and preventionrdquo Wiley Interdisci-plinary Reviews vol 2 no 6 pp 693ndash702 2010

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

6 Journal of Nanotechnology

646421 plusmn 114908 ngmL after oral dosing whereasin the case of AZT-SLNs observed mean peak plasmaconcentration was 399221 plusmn 22388 ngmL both appeared at119879max of 15min It was seen during study that 119862max associatedwith AZT-SLNs was less as compared to AZT solution butat the same time the AUC

0ndashinfin associated with AZT-SLNswas significantly higher than AZT solution The reasonbehind this type of kinetic behavior is because of the lipidshell surrounding the drug core which leads to the decreasein instant absorption of drug through stomach which isnot possible in case of simple solution The same is alsohelpful for explaining the extended release pattern whenformulation goes through the intestine Reportedmechanismof absorption of SLNs is mainly through Peyerrsquos patches byintracellular uptake or paracellular pathway The absorptionbehavior in this system is reported to enable bypass of gastricand intestinal degradation of the encapsulated drug and theirpossible uptake and transport through intestinal mucosa[24] It is also reported that adhesive properties due to thelipid shell increases bioavailability and reduces or minimizeserratic absorption [25 26] Despite these discussions nodata has been published so far concerning the stability ofSLNs in the GI tract The change in excretion pattern of AZTwith respect to SLNs is due to the change in distributionpattern of AZT This is due to the lymphatic absorption ofSLNs which leads to decrease in first pass metabolism ofthe drug through hepatic recirculation Significant decreasein clearance (119875 lt 001) and increase in MRT (119875 lt 0001)indicate targeting of drug directly to organs without goinginto systemic circulationThis happened due to the lymphaticabsorption of SLNs from GI tract which is supported by thetissue distribution study [27]

Higher concentrations in various tissues are essential forits pharmacological roles In the present study the ratio of119862max in the brain after administration of AZT-SLNs andAZT solution was 192 and the ratio of AUC

0ndash6 h in thebrain was 273 Based on the previous studies it is reportedthat increasing concentration of AZT in the brain is usefulfor the treatment of dementia associated with HIV uponthe intragastric administration of AZT-SLNs Under normalconditions drug penetration into the brain is restricted bythe blood brain barrier (BBB)Themechanisms for transportof SLNs through the BBB are not completely understoodThe little decrease in ratios of 119862max and AUC

0ndash6 h in heartand kidney indicated that lesser AZT was taken up in thesystemic circulation which helps in reduction of toxicityof AZT like bone marrow suppression The 119879max for AZTsolution and AZT-SLNs were 30 and 45 respectively whichindicates delayed penetration of SLNs into liver leading toincreased effectiveness of formulation by delaying first passmetabolism of drug into the liver Use of AZT-SLNs alsoresulted in decreased concentration of AZT in kidney leadingto slower excretion rate increasing the MRT It is possiblethat lipid associated with AZTmay have altered the excretionprofile because AZT itself being a water-soluble drug hasfaster excretion as compared to AZT-SLNs Graph representsthat distribution of AZT-SLN in brain was biphasic and 119879maxachieved was slower and delayed up to 30min while in caseof AZT solution it was achieved at 15min

When AZT is incorporated into nanoparticles the prop-erties of the SLNs will determine the in vivo disposition ofdrug The clearance of nanoparticles from blood circulationis done by themononuclear phagocyte system (MPS) Resultsindicate that AZT-SLNs might have been taken up in thegastrointestinal tract and translocated to the organs con-taining MPS After intragastric administration of AZT-SLNsthey were rapidly absorbed and distributed well to targettissue that is brain after a single dose administration It alsoexhibited the extended release pattern which was indicatedby its release kinetics Collectively the data indicate that SLNsare a guaranteed delivery system for the enhancement of oralabsorption of zidovudine a water-soluble drug

5 Conclusion

The present study has demonstrated that the intragastricadministration of AZT-SLNs provided prolonged drug deliv-ery and increased the AZT level in brain It can be a potentialformulation for the treatment of HIV Outcomes of this studyhave provided a basis to conduct further studies in HIVpatients

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors are thankful to All India Council for TechnicalEducation (AICTE New Delhi India) for their generoussupport of this work Purvin Shah also gratefully acknowl-edges the financial assistance provided by University GrantCommission (UGC New Delhi India) in the form of JuniorResearch Fellowship for the partial fulfillment of the require-ments for the degree of Master of Pharmacy

References

[1] M A Fischl D D Richman N Hansen et al ldquoThe safetyand efficacy of zidovudine (AZT) in the treatment of subjectswith mildly symptomatic human immunodeficiency virus type1 (HIV) infection A double-blind placebo-controlled trialrdquoAnnals of Internal Medicine vol 112 no 10 pp 727ndash737 1990

[2] G J Veal and D J Back ldquoMetabolism of zidovudinerdquo GeneralPharmacology vol 26 no 7 pp 1469ndash1475 1995

[3] S Singh A K Dobhal A Jain J K Pandit and S ChakrabortyldquoFormulation and evaluation of solid lipid nanoparticles of awater soluble drug zidovudinerdquo Chemical and PharmaceuticalBulletin vol 58 no 5 pp 650ndash655 2010

[4] J das Neves M M Amiji M F Bahia and B SarmentoldquoNanotechnology-based systems for the treatment and preven-tion of HIVAIDSrdquo Advanced Drug Delivery Reviews vol 62no 4-5 pp 458ndash477 2010

[5] P S Kim and S W Read ldquoNanotechnology and HIV potentialapplications for treatment and preventionrdquo Wiley Interdisci-plinary Reviews vol 2 no 6 pp 693ndash702 2010

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Journal of Nanotechnology 7

[6] R Mallipeddi and L C Rohan ldquoProgress in antiretroviraldrug delivery using nanotechnologyrdquo International Journal ofNanomedicine vol 5 no 1 pp 533ndash547 2010

[7] P R Ravi U K Kotreka and R N Saha ldquoControlled releasematrix tablets of zidovudine effect of formulation variables onthe in vitro drug release kineticsrdquo AAPS PharmSciTech vol 9no 1 pp 302ndash313 2008

[8] A Kuksal A K Tiwary N K Jain and S Jain ldquoFormulationand in vitro in vivo evaluation of extended-release matrix tabletof zidovudine influence of combination of hydrophilic andhydrophobic matrix formersrdquo AAPS PharmSciTech vol 7 no1 pp E1ndashE9 2006

[9] C D Kaur M Nahar and N K Jain ldquoLymphatic targetingof zidovudine using surface-engineered liposomesrdquo Journal ofDrug Targeting vol 16 no 10 pp 798ndash805 2008

[10] N C Phillips and C Tsoukas ldquoLiposomal encapsulation ofazidothymidine results in decreased hematopoietic toxicity andenhanced activity against murine acquired immunodeficiencysyndromerdquo Blood vol 79 no 5 pp 1137ndash1143 1992

[11] S Jain A K Tiwary and N K Jain ldquoPEGylated elasticliposomal formulation for lymphatic targeting of zidovudinerdquoCurrent Drug Delivery vol 5 no 4 pp 275ndash281 2008

[12] U Y Nayak S Gopal S Mutalik et al ldquoGlutaraldehydecross-linked chitosan microspheres for controlled delivery ofZidovudinerdquo Journal of Microencapsulation vol 26 no 3 pp214ndash222 2009

[13] K Abu-Izza L Tambrallo and D R Lu ldquoIn vivo evaluationof zidovudine (AZT)-loaded ethylcellulose microspheres afteroral administration in beagle dogsrdquo Journal of PharmaceuticalSciences vol 86 no 5 pp 554ndash559 1997

[14] H Hillaireau T Le Doan M Appel and P CouvreurldquoHybrid polymer nanocapsules enhance in vitro delivery ofazidothymidine-triphosphate to macrophagesrdquo Journal of Con-trolled Release vol 116 no 3 pp 346ndash352 2006

[15] Y-C Kuo and H-H Chen ldquoEffect of nanoparticulate poly-butylcyanoacrylate and methylmethacrylate-sulfopropylmeth-acrylate on the permeability of zidovudine and lamivudineacross the in vitro blood-brain barrierrdquo International Journal ofPharmaceutics vol 327 no 1-2 pp 160ndash169 2006

[16] R M Mainardes M P D Gremiao I L Brunetti M D LuizFonseca and N M Khalil ldquoPharmaceutical nanotechnologyzidovudine-loaded PLA and PLA-PEG blend nanoparticlesinfluence of polymer type on phagocytic uptake by polymor-phonuclear cellsrdquo Journal of Pharmaceutical Sciences vol 98 no1 pp 257ndash267 2009

[17] R Lobenberg L Araujo H Von Briesen E Rodgers and JKreuter ldquoBody distribution of azidothymidine bound to hexyl-cyanoacrylate nanoparticles after iv injection to ratsrdquo Journalof Controlled Release vol 50 no 1ndash3 pp 21ndash30 1998

[18] R M Mainardes N M Khalil and M P D Gremiao ldquoIntra-nasal delivery of zidovudine by PLA and PLA-PEG blendnanoparticlesrdquo International Journal of Pharmaceutics vol 395no 1-2 pp 266ndash271 2010

[19] A Dembri M-J Montisci J C Gantier H Chacun andG Ponchel ldquoTargeting of 31015840-azido 31015840-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gas-trointestinalmucosa and associated lymphoid tissuesrdquo Pharma-ceutical Research vol 18 no 4 pp 467ndash473 2001

[20] P M Ved and K Kim ldquoPoly(ethylene oxidepropylene oxide)copolymer thermo-reversible gelling system for the enhance-ment of intranasal zidovudine delivery to the brainrdquo Interna-tional Journal of Pharmaceutics vol 411 no 1-2 pp 1ndash9 2011

[21] S T K Narishetty and R Panchagnula ldquoTransdermal deliverysystem for zidovudine in vitro ex vivo and in vivo evaluationrdquoBiopharmaceutics and Drug Disposition vol 25 no 1 pp 9ndash202004

[22] M E BrewsterW R Anderson A IWebb et al ldquoEvaluation ofa brain-targeting zidovudine chemical delivery system in dogsrdquoAntimicrobial Agents and Chemotherapy vol 41 no 1 pp 122ndash128 1997

[23] Y Jin N Qi L Tong and D Chen ldquoSelf-assembled drugdelivery systems Part 5 self-assemblies of a bolaamphiphilicprodrug containing dual zidovudinerdquo International Journal ofPharmaceutics vol 386 no 1-2 pp 268ndash274 2010

[24] S Chakraborty D Shukla B Mishra and S Singh ldquoLipidmdashan emerging platform for oral delivery of drugs with poorbioavailabilityrdquoEuropean Journal of Pharmaceutics andBiophar-maceutics vol 73 no 1 pp 1ndash15 2009

[25] A Zur Muhlen C Schwarz and W Mehnert ldquoSolid lipidnanoparticles (SLN) for controlled drug deliverymdashdrug releaseand release mechanismrdquo European Journal of Pharmaceuticsand Biopharmaceutics vol 45 no 2 pp 149ndash155 1998

[26] R H Muller K Mader and S Gohla ldquoSolid lipid nanoparticles(SLN) for controlled drug deliverymdasha review of the state of theartrdquo European Journal of Pharmaceutics and Biopharmaceuticsvol 50 no 1 pp 161ndash177 2000

[27] M Uner and G Yener ldquoImportance of solid lipid nanoparticles(SLN) in various administration routes and future perspectivesrdquoInternational Journal of Nanomedicine vol 2 no 3 pp 289ndash3002007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials