A Comparison of Zidovudine (AZT) Used Alone or in Combination With Didanosine (ddI) or Dideoxycytidine (ddC) in HIV-Infected Patients

Primary: To compare the efficacy of zidovudine ( AZT ) given alone versus AZT plus didanosine ( ddI ) versus AZT plus zalcitabine ( dideoxycytidine; ddC ) in delaying the occurrence of AIDS-related conditions in HIV-infected patients. Secondary: To compare the frequency and severity of adverse experiences in the three regimens. To compare the mortality rates in the three regimens. To compare the effects of antiretroviral regimens on CD4+ cell levels. Studies have indicated that maintenance therapy with AZT over extended periods may be limited by dose-dependent toxicity, primarily myelosuppression, and by the emergence of drug-resistant HIV strains. It is anticipated that the combination of AZT with either ddI or ddC may promote higher antiviral efficacy, with acceptable toxicity and less likelihood of development of drug-resistant strains, than AZT alone.

Studies have indicated that maintenance therapy with AZT over extended periods may be limited by dose-dependent toxicity, primarily myelosuppression, and by the emergence of drug-resistant HIV strains. It is anticipated that the combination of AZT with either ddI or ddC may promote higher antiviral efficacy, with acceptable toxicity and less likelihood of development of drug-resistant strains, than AZT alone. Approximately 1200 patients are randomized in a 2:1:1:2 ratio to one of the following four treatment arms: AZT plus ddI, AZT plus ddI placebo, AZT plus ddC placebo, and AZT plus ddC. Average follow-up is 2 years.