[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/) › Zidovudine [Pharmacology](https://durgical.com/en/pharmacology/) · [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/) # Zidovudine The first antiretroviral (AZT). Little used in adults today because of bone marrow toxicity, but still part of newborn prophylaxis. Updated 2026-11-01 - Class: [Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/) - Enzyme: HIV-1 reverse transcriptase - ATC code: J05AF01 - WHO Model List of Essential Medicines Also called: AZT, azidotimidina, ZDV ✂**HIV-1 reverse transcriptase**Zidovudine ⓘ The figure shows zidovudine triphosphate (AZT-TP), the active form, in the polymerase site of HIV-1 reverse transcriptase with DNA. **Target in 3D:** HIV-1 reverse transcriptase. PDB structure 3V4I (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/3V4I) · Drag to rotate · pinch to zoom ## Mechanism of action A thymidine analogue with an azido group instead of the 3'-hydroxyl. It is phosphorylated to zidovudine triphosphate, which competes with dTTP; incorporated into viral DNA, it ends the chain. It also partly inhibits human polymerases, especially the mitochondrial one, which explains myopathy and marrow toxicity. - It is phosphorylated to zidovudine triphosphate - It competes with dTTP at reverse transcriptase - The azido group blocks DNA chain extension ## Pharmacokinetics **Metabolism** Glucuronidation in the liver to an inactive metabolite **Elimination** Zidovudine and its glucuronide leave in urine; they build up in severe kidney failure ## Indications - HIV-1 infection, combined with other antiretrovirals [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/) - Prevention of mother-to-child HIV transmission [HIV infection and AIDS →](https://durgical.com/en/conditions/hiv-infection-and-aids/) ## Adverse effects ### Common - Nausea, headache, malaise - Macrocytosis - Changes in skin and nail pigmentation ### Serious (rare, important) - Severe anaemia and neutropenia - Symptomatic myopathy with long-term use - Lactic acidosis and hepatomegaly with steatosis ## Contraindications - Previous severe hypersensitivity (anaphylaxis, Stevens-Johnson) to zidovudine ## Key interactions **Ganciclovir, interferon alfa and other myelosuppressive or cytotoxic drugs** Additive bone marrow toxicity **Ribavirin** Worsens anaemia in HIV-hepatitis C co-infection; the combination is not advised **Stavudine** Antagonism between these two thymidine analogues has been shown: the combination is avoided ## What is monitored - Complete blood count (haemoglobin and neutrophils) regularly - Muscle symptoms and CK if myopathy is suspected - Lactate if acidosis symptoms appear - Viral load and CD4 ## Administration and safety - Available as capsules, syrup and intravenous injection (the latter mainly during labour) - In newborns, the liquid form needs careful checking of the ordered volume - Do not confuse zidovudine with similar-sounding drugs; check the abbreviation AZT on orders ## Nursing care - Check blood count before and during treatment - Watch for pallor, fatigue, fever or infections (anaemia, neutropenia) - Ask about muscle pain or weakness - In exposed newborns, coordinate prophylaxis as the team orders ## Pregnancy and breastfeeding It is approved to prevent mother-to-child HIV transmission and is now part of regimens for exposed newborns. ## Memory aid 'AZT = Anaemia, Zapped muscles (myopathy), Transmission to the baby prevented'. ## Test yourself Think of the answer, then tap the question to see it. ## What is zidovudine's most typical toxicity? Bone marrow suppression: anaemia (often macrocytic) and neutropenia. ## Why is zidovudine not combined with ganciclovir without close monitoring? Both are myelotoxic and their marrow effects add up. ## Which use of zidovudine is still relevant today? Preventing mother-to-child HIV transmission, mainly in newborn prophylaxis. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/zidovudine/) ## Related drugs - [Lamivudine](https://durgical.com/en/pharmacology/lamivudine/) - [Nevirapine](https://durgical.com/en/pharmacology/nevirapine/) ## Related conditions - [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/) [← Back to the class: Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)](https://durgical.com/en/pharmacology/classes/nucleoside-nucleotide-reverse-transcriptase-inhibitors/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - ZIDOVUDINE capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9907acb2-e4a0-46f9-93c0-a8d7b7ce98cf) (DailyMed (U.S. National Library of Medicine), 2025); [Zidovudine: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a687007.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J05AF01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/zidovudine/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/zidovudine/