Comparison of Once and Twice Daily Dosing of Didanosine in Combination with Stavudine for the Treatment of HIV-1 Infection

Objective To compare the antiviral activity, safety and tolerability of didanosine dosed once and twice daily when administered in combination with stavudine dosed twice daily in human immunodeficiency virus type 1 (HIV-1)-infected individuals with little or no previous exposure to antiretroviral drugs. Design Comparative, multicentre, randomized, open-label, short-term study. Patients and Methods Eighty-four HIV-1-infected adults with qualifying baseline CD4 cell counts of 200 to 500 cells/mm3 were included in the study. Of these, 43 patients received once daily didanosine plus twice daily stavudine (group A) and 41 subjects received twice daily didanosine plus twice daily stavudine (group B). The primary efficacy analysis used was the time-averaged difference (TAD) between treatment regimens of variations in plasma HIV-1 RNA levels from baseline over the first 12 weeks of therapy. Plasma HIV-1 RNA levels, CD4 cell counts and adverse events were monitored. Results: At week 12, median HIV-1 RNA variations were –1.18 log10 copies/ml in group A and –0.88 log10 copies/ml in group B. For patients who were followed up to week 24, median variations of HIV-1 RNA levels from baseline were –1.21 log10 copies/ml in group A and –0.78 log10 copies/ml in group B. The TAD between the two treatment groups for variations from baseline plasma HIV-1 RNA levels over the first 12 weeks was 0.10 log10 copies/ml (95% confidence interval, –0.19 to 0.40), indicating equivalence. Conclusion Once daily didanosine plus twice daily stavudine and twice daily didanosine plus twice daily stavudine are equally effective in reducing plasma HIV-1 RNA levels and increasing CD4 cell counts. Both regimens are safe and well tolerated.