Alternating treatment with didanosine and zidovudine versus either drug alone for the treatment of advanced HIV infection. The Alter Study. Nordic HIV Therapy Group

The efficacy and safety of an alternating regime with zidovudine and didanosine versus treatment with either drug alone were investigated in a randomized, open, controlled trial, 552 patients with advanced HIV infection, 47% of whom had received prior treatment with zidovudine, were enrolled. The patients were randomly assigned to zidovudine 600 mg/day, didanosine 400 mg/day or 4-week alternations with the 2 drugs in the same dose. The study had a median length of follow-up of 88 weeks. In the overall analyses, time to death (p = 0.48) and time to death or new AIDA event (0.80) were equally distributed between the 3 treatment groups. In the subgroup of patients with a CD4 count <100 x 10(6)/l the survival was longer in the alternating arm (p <0.005) primarily because of differences among zidovudine naive patients. The alternating regime was better tolerated than the 2 monotherapies, with a longer time to dose reduction or withdrawal owing to side effects (p <0.001).