DOXYCYCLINE

Amin ullah Daavi

Roll no 215

OBJECTIVESIntroduction.Chemical structure of doxycycline.

Mechanism of action.Resistance.Antimicrobial activity.Clinical uses.Adverse effect.Contraindication.

INTRODUCTION Doxycycline is a

synthetic broad spectrum antibiotic drug derived from tetracycline which inhibit protein synthesis.

CHEMICAL STUCTURE

CLASSIFICATION OF TETRACYCLINEA. Short acting(6-8 hours) Chlortetracycline Oxytetracycline

B. Intermediate acting (12 hrs)

Demeclocycline Methacycline

C. Long acting(16-18 hours) Doxycycline Minocycline

MECHANISM OF ACTIONDoxycycline reversiably bind to 30s subunit at A site

Block the binding of aminoacyl t-RNA to m-RNA

inhibit the addition of new aminoacid to growing peptide chain

Stop the translation process

RESISTANCE Mechanism of resistance.

Impaired influx or increase effluxRibosomal protein production that interfere the binding of doxycycline

Enzymatic inactivation

RESISTANCE Tet (AE)efflux pump Resistance.

Tet(M) efflux pump Resistance.

Tet(K) efflux pump susceptible.

ANTIMICROBIAL ACTIVITY Doxycycline are sensitive against Many gram-positive and gram-negative

bacteria. Bacillus anthracis. Staphylococcus aureus. Listeria monocytogenes. Mycoplasma pneumoniae. Chlamydiae and spirochetes. Rickettsiae . Vibrio cholera. Neisseria gonorrhoea. Haemophilus influenzae.

CLINICAL USES Doxycyline is the drug of choice in infaction

caused by Mycoplasma Pneumonia. Rickettsiae Rocky mountain

spotted fever and rickettsial

pox. Chlamydia Trachoma and

peittacosis. Vibrio Cholera. Bacillus anthracis Anthrax. Spirochetes Lyme’s disease.

CLINICAL USES Doxycycline use in a regimen for

treatment of gastic ulcer caused by helicobacter pylori

Also with amino glycoside for plague, tularemia and brocellosis

ADVERSE EFFECTSA. Gastrointestinal adverse effects Nausea vomiting and diarrhea.

B. Bony structures and teeth During pregnancy it can deposited in

fetal teeth leading to fluorescence ,discoloration and enamel dysplasia.

C. Liver toxicity Hepatic toxicity leading to hepatic

necrosis.

ADVERSE EFFECTD. Kidney

toxicity.E. Local tissue

toxicity.F. Vestibular

toxicity.G. Photosensitiz

ation.

CONTRAINDICATION Hypersensitivity

Pregnancy

Infants and children

REFERENCES Basic and clinical pharmacology (11th edition)

Chapter 44(796-799)

Lippincoatt’s illustrated reviews Pharmacology (4th edition)

chapter 32(373-376)

httpwww.drugs.comdoxycycline.html

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