Zidovudine (AZT)

Zidovudine (AZT)
Zidovudine is an effective anti-viral drug that acts on retroviruses especially human immunodeficiency virus (HIV).
It is not preferred 1st line antiviral drug according to regimen 2016 of WHO. 

• Zidovudine belongs to nucleoside reverse transcriptase inhibitors class of anti-retroviral drugs.

• The therapeutic dose of zidovudine for adults is 300 mg and 180 mg per meter square for children.
• Zidovudine is also known as AZT due to its usage as a thymidine analogue.
• Mechanism of action(MOA):- Zidovudine when administered, get phosphorylation in the host cell and converted into zidovudine triphosphate. The zidovudine triphosphate selectively inhibits viral reverse transcriptase in preference to DNA polymerase.
• AZT inhibits HIV reverse transcription by replacing thymidine from DNA formed by the reverse transcription process and results in changing of the base sequence of DNA, which makes it an inactive DNA and stops further DNA reverse transcription.
• Thus zidovudine prevents infection of new cells of the host but fails to damage viral genome, hence cannot eliminate the virus from the host but can stop the growth of virus in the host body.

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• AZT oral absorption is rapid but bioavailability is only up to 65% of the total drug, 15-20% of the unchanged drug is excreted through urine.
• AZT can cross the placenta and is found in the milk of a mother who has past record of AZT treatment.
• Paracetamol increases AZT toxicity by competing for glucuronidation.
• Azole antifungal drugs inhibit AZT metabolism.
• Stavudine and zidovudine exhibit mutual antagonism by competing for the same activation pathway.
• zidovudine or AZT is marketed in the trade name of:-

1. Retrovir:-
2. Zidovir:-                                                                                       
3. Viro-Z:-                                                                                         
4. Zidomax:-
5. Zydowin:-

• The adverse effect (side effect) caused by Zidovudine includes:-

1. Anaemia
2. Neutropenia
3. Nausea
4. Vomiting
5. Anorexia
6. Abdominal pain
7. Headache
8. Insomnia
9. Pigmentation of nail
10. Lactic acidosis
11. Hepatomegaly
12. Myopathy

Reference:- K.D Tripathi Medical Pharmacology 8th Edition.