A Randomized, Double Blind, Comparative Study of Dideoxycytidine (ddC) Alone or ddC/AZT Combination Versus Zidovudine (ZDV) Alone in Patients With HIV Infection Who Have Received Prior ZDV Therapy

To evaluate the safety of zalcitabine (dideoxycytidine; ddC) alone and in combination with zidovudine (AZT) versus AZT alone when administered to asymptomatic patients with a CD4 count = or < 200 cells/mm3 and symptomatic patients with a CD4 count = or < 300 cells/mm3. To compare the effectiveness of ddC alone and in combination with AZT versus AZT alone. ddC has been shown to demonstrate an antiviral effect. AZT has been shown to significantly decrease mortality and reduce the frequency of opportunistic infections in patients with AIDS or advanced ARC. After 1 year of AZT therapy, the effectiveness tends to diminish and patients progress with more opportunistic infections and higher mortality rates. Because of the demonstrated antiviral activity, absence of hematologic toxicity, and lack of cross tolerance in laboratory studies of ddC, a study to investigate the long-term effectiveness of ddC in patients with HIV infection who have received AZT therapy is warranted. ddC has been shown to demonstrate an antiviral effect. AZT has been shown to significantly decrease mortality and reduce the frequency of opportunistic infections in patients with AIDS or advanced ARC. After 1 year of AZT therapy, the effectiveness tends to diminish and patients progress with more opportunistic infections and higher mortality rates. Because of the demonstrated antiviral activity, absence of hematologic toxicity, and lack of cross tolerance in laboratory studies of ddC, a study to investigate the long-term effectiveness of ddC in patients with HIV infection who have received AZT therapy is warranted. Patients are randomly assigned to 1 of 3 treatment groups. In study arm 1, patients receive AZT plus ddC placebo. In study arm 2, patients receive ddC plus AZT placebo capsules. In study arm 3, patients receive ddC plus AZT. Patients are seen every other week for first 8 weeks and monthly thereafter. Patients are stratified by HIV disease status, length of time receiving AZT, and systemic or local Pneumocystis carinii pneumonia (PCP) prophylaxis. Patients who reach a clinical AIDS-defining endpoint are offered open-label combination therapy.