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 AZIDOTHYMIDINE (AZT) / ZIDOVUDINE  BRAND NAME:- RETROVIR, ZIDOVIR 100mg cap,50mg/5ml syr ,VIRO-Z , ZIDOMAX , ZYDOWN 100 mg cap, 300 mg tab. AZT / ZIDOVUDINE is a thymidine analogue,the prototype NRTI. After phosphorylation in the host cell- zidovudine triphosphate selectively inhibits viral reverse transcriptase in preference to cellular DNA polymerase. PHARMACOKINETICS:-  The oral absorption of AZT is rapid ,but bioavailability is ~ 65% . It is quickly cleared by hepatic glucuronidation (t½ 1 hr) ; 15-20% of the unchanged drug along with the metabolite is excerted in urine. Plasma proteins  binding is 30% and CSF level ~ 50% of that in plasma. It crosses placenta and is found in milk. PHARMACODYNAMIC:- Zidovudine is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1). Zidovudine is phosphorylated to active metabolites that compete for incorporation into viral DNA. They inhibit the HIV reverse transcr...