A Phase II Efficacy Study Comparing 2',3'-Dideoxyinosine (ddI) (BMY-40900) and Zidovudine Therapy of Patients With HIV Infection Who Have Been on Long Term Zidovudine Treatment

AZT is effective in reducing mortality in patients with AIDS who receive the drug after the first episode of Pneumocystis carinii pneumonia (PCP) and in patients with advanced ARC. However, AZT therapy has been associated with significant toxicities. In addition, the effectiveness of AZT appears to decrease during the second and third years of therapy. For these reasons, the development of alternative therapy that would be at least as effective but less toxic is of great importance. The drug ddI is an antiviral agent that inhibits replication of HIV with less apparent toxicity than AZT. Studies indicate that ddI remains active in the body for at least 12 hours; thus benefits of ddI might be achieved with a low frequency of drug administration. Two dose levels of ddI, each adjusted depending on patient's weight at study entry, are compared with a variable dosage regimen of AZT (the dose which the patient is tolerating at the time of study entry). Randomization is stratified by baseline CD4 cell count (less than 100 or 100-300) and Medical Center. This study continues for at least 12 months after the entry of the first subject. Patients randomized to AZT will receive orally. All patients randomized to AZT also receive a ddI placebo at 12 hour intervals. Patients randomized to ddI receive AZT placebo.