Zidovudine (Retrovir)

Published January 25, 2001; Updated February 2013
Susa Coffey, MD
http://hivinsite.ucsf.edu/InSite?page=ar-01-01
Selected Reference
7. Larder  BA, Kemp  SD, Harrigan  PR.
Potential mechanism for sustained antiretroviral efficacy of AZT-3TC combination therapy. Science. 1995 Aug;269(5224):696-9
[PubMed ID: 7542804]
Abstract:
Combinations of antiretroviral drugs that prevent or delay the appearance of drug-resistant human immunodeficiency virus-type 1 (HIV-1) mutants are urgently required. Mutants resistant to 3'-azidothymidine (AZT, zidovudine) became phenotypically sensitive in vitro by mutation of residue 184 of viral reverse transcriptase to valine, which also induced resistance to (-)2'-deoxy-3'-thiacytidine (3TC). Furthermore, AZT-3TC coresistance was not observed during extensive in vitro selection with both drugs. In vivo AZT-3TC combination therapy resulted in a markedly greater decreased in serum HIV-1 RNA concentrations than treatment with AZT alone, even though valine-184 mutants rapidly emerged. Most samples assessed from the combination group remained AZT sensitive at 24 weeks of therapy, consistent with in vitro mutation studies.