Pharmaceutical Emulsions

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Pharmaceutical Emulsions. PHT 3101 Sept 2012 By: Imanirampa Lawrence(MPS). “ Emulsions ” :preparations intended for internal use( i.e via oral route Emulsion :others for external, always given different titles whc reflects their use(applications, lotions, creams etc..) - PowerPoint PPT Presentation

Text of Pharmaceutical Emulsions

  • Pharmaceutical Emulsions

    PHT 3101

    Sept 2012By: Imanirampa Lawrence(MPS)

  • INTRODUCTIONEmulsions :preparations intended for internal use( i.e via oral routeEmulsion :others for external, always given different titles whc reflects their use(applications, lotions, creams etc..)Emulsion - a liquid preparation, contains two immiscible liquids(oil and water), one is finely sub divided and uniformly distributed as droplets in the diversion media ,rendered homogenous/stabilized by addition of an emulgent(emulsifying agent)

  • Emulgent : ensures the oil phase is finely dispersed throughout the water as minute globulesType of emulsion: 1. oil-in water (O/W)typeAll oral dose emulsions= o/w type, w/o emulsions- intended for external use

    why? Oily phase-less present to take,Are difficulty to flavor

  • BP: oral Emulsion an oral liquid, contain one or more active ingredientso/w dispersions, either or both phases may contain dissolved solids(suspended in oral emulsion)Packaged in wide-mouthed bottles2. w/o emulsion for external use3. w/o/w emulsions4. o/w/o emulsions

  • Purpose of emulsions and emulsificationEmulsification:Enables pharmacist prepare relatively stable, homogenous mixtures of two immiscible liquids(oil and water soluble drugs)Permits administration of a liquid drug in the form of minute globules rather than bulkyo/w permits palatable administration of an otherwise distasteful oil, dispersing in a sweetened ,flavored aqueous vehicle Reduction of size of oil globules may render the oil more digestible and more readily absorbed, more effective in its task(increased

  • Oral,rectal and topical emulsions (o/w or w/o) administration of oils oil soluble drugs Medicinal agent-irritant to the skin, less irritating Naturally, miscibility or solubility in oil and in water of a medicinal agent dictates to a greater extent the vehicle IM of some water-soluble vaccines provide a slow release(greater response and long lasting immunity)Total parenteral nutrition-sterile o/w emulsion-delivering oily nutrients IVsly

  • On unbroken skin-w/o emulsion applied more evenly,-skin is covered with thin film of sebum w/o is more softening to the skin,

    Preparation -removed easily from the skin, o/w emulsion is preferredDiminished particle size of internal phase (percutaneous absorption) may be enhancedIM

  • Advantages of emulsions as dosage forms Unpalatable drug -administered in palatable liquid form(code liver oil emulsion) Unpalatable oil-soluble drugs-administered in a palatable form Aqueous phase - easily flavoredOily sensation - easily removedIncreased rate of absorptionPossible to include two incompatible ingredients in each phase of the emulsion

  • Disadvantages of emulsions as dosage forms Preparation needs shaking well before use

    Measuring device needed in administration

    Need degree of technical accuracy to measure a dose

    Storage conditions may affect stability

    Bulky, difficult to transport and prone to container breakagesReliable to microbial contamination whc can lead to crack

  • Physical properties ofsuspension and emulsions:-Flocculation and deflocculated sytems-Rheology-Viscosity modifiers

  • Physical properties of suspensions and emulsions Pdt - sufficiently homogenous on shaking the container and removing required amount

    storage no sedimentation or creaming if so happen resuspended Pdt - thickened in order to reduce the rate of creaming of oily globules

    Resulting viscosity in right proportions- ease of removal or transfer from container

  • Physical properties of suspensions and emulsionsSuspended particles should be small and uniformly sized in order to-smooth, -elegant pdt, -non gritty

  • Flocculation and defloculated sytem Read chapt6,pg90-97 and chapt27, pg 386,pharmaceutics by M.E.Aulton and make some brief notes with few diagrams to illustrate the two terms.

  • RheologyREO means flowLOGY means science of flowAn ideal p,ceutical suspension exhibit a high apparent viscosity at low rates of shear so that on storage,suspended particles would either settle slowly /preferably, remain permanently suspended At higher rates of shear, such as those caused by moderate shaking of pdt, the apparent viscosity shd fall sufficiently for the pdt to be poured easily from the container

  • Rheology Pdt for external use shd spread easily without excess drugging, but shd not be so fluidy that it runs off the surface If intended for inj the pdt shd pass easily thru the hypodermic needle with only moderate pressure applied to the plunger Its important for the initial high apparent viscosity to be reformed after a short time to maintain adequate physical stability(further reading ref chapt 4 ,Aulton)

  • Rheology Describe following terms:Plastic (Bingham) flowPseodoplastic flowDilatant flowThixotropyDilatancyIdentify and describe several methods by which rheological properties of an emulsion can be controlled.

  • Viscosity modifiers

    Materials -most widely used for the modification of suspension viscosityPolysaccharides(acacia,tragacanth,alginate starch,xanthan gum)Water soluble cellulose(methyl cellulose,hydroxyethylcellulose,SCMC, microcrystalline)Hydrated silicates(bentonite,mg aluminium silicate,hectorite)Carbomers(colloidal silicon dioxide)

  • Polysaccharides

    Acacia Is a natural material,suspending agent for extemporaneously prepared suspensions Not a good thickening agent largely used due to its action as a protective colloid. Useful in tinctures of resinous materials formulations whc ppte on addition to water coats precipitated resin, forming protective colloid before any electrolyte(which should be well diluted) is added.Not very effective for dense powders, remedy combin with other thickener(tragacanth,starch and sucrose)

  • Polysaccharides Tragacanth: Form viscous aqueous solutions

    Its thixotropic and pseudoplastic properties make it a better thickening agent than acacia used both for internal and external products Like acacia it is used for the extemporaneous preparation of suspensions with a short shelf-lifeStable over a pH range of 4-7.5

  • Polysaccharides

    Takes several days to hydrate fully after dispersion in water is the period for maximum viscosity of its dispersions and is heating labileHas several grades and best quality of these is a suitable pharmaceutical suspending agent.

  • PolysaccharidesAlginates

    Alginic acid, a polymer of D-mannuronic acid Prepared from kelp, and its salts have suspending properties similar to those of tragacanth Alginate mucilages must not be heated above 60C -depolymerization - loss in viscosity Are most viscous immediately ,but fall to a fairly constant value after about 24 hours.

  • Alginates maximum viscosity over a pH range of 5-9, and pptes at low pH Sodium alginate (Manucol) -most widely used material in this class is anionic therefore incompatible with cationic materials and heavy metals calcium chloride + sodium alginate dispersion = calcium alginate,with much higher viscosityOTHERS: Starch Xanthan gum

  • Water-soluble celluloses

    Several cellulose derivatives are available that will disperse in water to produce viscous colloidal solutions suitable for use as suspending agentsexamples: Methylcellulose Hydroxyethylcellulose Carmellose sodium (sodium carboxymethylcellulose Microcrystalline cellulose

  • Water-soluble celluloses

    MethylcelluloseIs a semi-synthetic polysaccharide produced by the methylation of cellulose Several grades exist-depending on their degree of methylation and chain length longer the chain, more viscous is its solutioni.e. , a 2% solution of methylcellulose 20 exhibits an apparent viscosity of 20 millipascal seconds (mPa s) and methylcellulose 4500 has value of 4500 mPa s at 2% concentration

  • Hydrated silicates

    Classified into: 1. Bentonite, 2. Magnesium aluminium silicate (aka veegum,orattapulgite) and3. Hectorite, and Belong to a group called montmorillonite clays Hydrate readily, absorbing up to 12 times their weight of water, particularly at elevated temperatures. Form gels that are thixotropic and therefore have useful suspending propertiesAs with most naturally occurring materials they may be contaminated with spores, and this must be borne in mind when considering a sterilization process and choosing a preservative system

  • Carbomers Aka carboxypolymethylenes

    Are totally synthetic copolymer of acrylic acid and allyl sucrose

    its concentrations of up to 0.5%- used mainly for external application, and some grades can be taken internally

    forms acidic, low-viscosity solutions when dispersed in water and at pH between 6 and 11, become highly viscous

  • Colloidal silicon dioxide Aka AerosilWhen dispersed in water this finely divided

    Product will aggregate, forming a three-dimensional network

    concns up to 4% for external use,

    used for thickening non-aqueous suspensions

  • Types of EmulsionAn oil-in-water (o/w) emulsion is a system where the oil (internal phase) is dispersed throughout the aqueous (external) phase. A water-in-oil (w/o) emulsion is a system where the water is dispersed throughout the oil.Multiple emulsions may also be achieved (w/o/w or o/w/o) May be of interest when formulating delayed release products. Emulsions and creams are similar to suspensions because they are fundamentally unstable systems

  • Tests for identification of emulsion typeSeveral simple methods are available for distinguishing between o/w and w/o emulsions The most common of these involve: Miscibility tests with oil or water: emulsion- miscible with liquids