Azidothymidine, also called RetrovirTM, zidovudine, or ZDV. The first antiretroviral drug against HIV infection to be approved by the FDA (1987). A thymidine (RNA constituent) analog that suppresses replication of HIV. AZT is increasingly administered in combination with other antiviral drugs. Possible side effects include bone marrow suppression leading to anemia, leukopenia, or neutropenia; nausea; muscle weakness; and headaches.