Stavudine - A review of its pharmacodynamic and pharmacokinetic properties and clinical potential in HIV infection

Stavudine is a nucleoside analogue which undergoes intracellular phosphorylation to its active metabolite, stavudine-5'-triphosphate. At clinically relevant concentrations, the active metabolite restricts HIV replication by inhibiting the inclusion of thymidine-5'-triphosphate into proviral DNA by HIV reverse transcriptase, and/or by causing DNA chain termination. Viral resistance to stavudine does not commonly develop during treatment. Where it has developed, up to a 12-fold increase in resistance has been observed in clinical isolates from patients treated with stavudine for long periods. Stavudine 40mg twice daily and zidovudine 200mg 3 times daily were compared in 822 patients at various stages of HIV infection who had previously received long term zidovudine therapy. Stavudine was superior for both primary and surrogate end-points including clinical progression, treatment failure, increase in CD4+ cell counts and bodyweight gain. In a larger study, stavudine 40mg twice daily provided greater benefit than stavudine 20mg twice daily in terms of weight gain, haematological findings and the number of hospitalisations in 11 784 patients intolerant of, resistant to, zidovudine and didanosine. Peripheral neuropathy is the major dose-limiting adverse event associated with stavudine therapy and occurred more frequently with stavudine than zidovudine. However, haematological adverse events were observed less frequently with stavudine than with zidovudine. Thus, stavudine is effective in alleviating signs and symptoms of HIV infection in patients intolerant of, or no longer responding to, zidovudine or didanosine. It is also more effective than zidovudine in slowing disease progression in patients previously treated with zidovudine for long periods. The results of studies which will reveal the role of stavudine therapy in untreated patients and in combination with other anti-HIV agents are awaited with interest.