AZT is a thymidine nucleoside analog that inhibits reverse transcriptase and is clinically used to treat HIV/AIDS. AZT inhibits viral DNA synthesis, preventing viral replication; at high doses, it may inhibit DNA polymerase. Use of AZT is often limited

A nucleoside reverse transcriptase inhibitor that, following triphosphorylation by thymidine kinase, potently blocks replication of HIV (EC₅₀ = 3 nM) with low cytotoxicity (CC50 > 5 μM).