Inclusion Criteria

Required:

• Prior zidovudine (AZT) therapy for 9 months.

Concurrent Medication:

Allowed:

• Chemoprophylaxis for Pneumocystis carinii pneumonia (PCP) with aerosolized pentamidine of 300 mg every 4 weeks through the Respirgard II nebulizer.
• Maintenance treatment with pyrimethamine, sulfadiazine, amphotericin, fluconazole, ketoconazole, acyclovir, or inhaled pentamidine for subjects who have recovered from toxoplasmosis, cryptococcosis, candidiasis, herpes infection, or PCP.
• Dapsone for PCP.
• Pyrimethamine-sulfadoxine for toxoplasmosis.
• Ganciclovir (DHPG) for maintenance only for cytomegalovirus (CMV) retinitis.
• Note: Any approved medications can be used to treat an opportunistic infection. All concurrent medications should be kept to a minimum and recorded.

Patients must be positive for HIV by ELISA test and must have been receiving zidovudine (AZT) therapy for at least 9 months and have received AZT within 90 days prior to entry into the study.

Patients may be transfusion dependent as long as no more than 3 units of blood are needed in a 21-day period and the hemoglobin does not fall below 6.4 g/dl on two consecutive occasions despite the transfusions.

Exclusion Criteria

Concurrent Medication:

Excluded:

• Antiretroviral study medications other than zidovudine (AZT) and biologic response modifiers.
• Corticosteroids and chronic aspirin.
• Cimetidine.
• Flurazepam.
• Indomethacin.
• Ranitidine.
• Probenecid.
• Other experimental medications.

Patients will be excluded from the study for the following reasons:

• Removal from zidovudine (AZT) during treatment on ACTG protocol 002 for recurrent grade 4 toxicity.
• Removal from prior dideoxycytidine (ddC) therapy for peripheral neuropathy = or > grade 3.
• Visceral or extensive Kaposi's sarcoma requiring therapy or another malignancy requiring therapy.
• Toxicity grades according to NIAID Recommendations for Grading Acute and Subacute Toxic Effects (Adults).

Prior Medication:

Excluded:

• Antiretroviral study medications other than zidovudine (AZT) and biologic response modifiers.
• Patients may not have visceral or extensive Kaposi's sarcoma requiring therapy or another malignancy requiring therapy.