Comparison of twice-daily stavudine plus once- or twice-daily didanosine and nevirapine in early stages of HIV infection : the Scan Study

To evaluate the safety and effectiveness of once-daily didanosine and nevirapine plus twice-daily stavudine versus twice-daily administration of all three drugs. This open-label, randomized, multicentre study enrolled 94 antiretroviral-naive patients with chronic HIV infection, CD4+ cell counts > 500 x 10(6) cells/l, and viral loads > 5000 copies/ml. Patients were treated with either 40 mg stavudine (twice daily) plus 400 mg didanosine (once daily) and 400 mg nevirapine (once daily) or 40 mg stavudine (twice daily) plus 200 mg didanosine (twice daily) and 200 mg nevirapine (twice daily). After 12 months, 68% of patients who received twice-daily didanosine and nevirapine had viral loads < 200 copies/ml in the intention-to-treat and 79% in the on-treatment analysis, respectively. The corresponding values for patients treated with didanosine and nevirapine, taken once-daily, were 73 and 85%. The percentages of patients in each group with viral loads < 5 copies/ml at 12 months were 40% (once daily ) and 45% (twice daily) for the intention-to-treat analysis. Five of 11 patients (45%) with plasma viral loads < 5 copies/ml at 12 months had detectable virus in tonsillar tissue. Genotypic resistance to nevirapine was noted in seven of the 14 patients with detectable viral load at month 12. Mean changes in CD4+ cell counts for patients treated with stavudine plus once- or twice-daily didanosine and nevirapine were 154 and 132 x 10(6) cells/l, respectively. Treatment was interrupted due to adverse events in seven patients (8%) (four who received once-daily didanosine and nevirapine and three treated with twice-daily doses). The combination of twice-daily stavudine plus once-daily didanosine and nevirapine was as safe and well tolerated as twice-daily administration of all three agents. Both regimens were equally effective in reducing viral loads and in increasing CD4+ cell counts.