A Comparison of Three Treatments for Advanced HIV Disease in Patients Who Have Received Nucleoside Therapy in the Past

To compare the efficacy, safety and tolerance, and other clinical and immunologic effects of zidovudine (AZT) plus zalcitabine (dideoxycytidine; ddC), AZT plus didanosine (ddI), and AZT alternating monthly with ddI as measured by differences in survival among HIV-infected persons who have received 6 or more months of nucleoside monotherapy and have a CD4 count greater than or equal to 50 cells/mm3. Combining two nucleoside drugs has the theoretical advantage of optimal protection against the evolution of resistant strains of HIV. However, one major problem with combination nucleoside therapy in patients with advanced disease is the increased toxicity resulting from such therapy. One approach to minimize toxicity while perhaps retaining some of the benefits of combination therapy is to alternate the two drugs.