A Phase II Study to Evaluate Pharmacokinetics, Safety, Tolerance and Activity of Dideoxycytidine (ddC) Administered in Combination With Zidovudine (AZT) in Stable, AZT-Treated Pediatric Patients With HIV Infection

Inclusion Criteria Concurrent Medication: Recommended: * PCP prophylaxis. Allowed: * Intravenous and/or intramuscular immunoglobulin. * Acyclovir (no more than 30 mg/kg/day PO). * Ketoconazole (no more than 10 mg/kg/day). * Nystatin. * Aspirin, acetaminophen, nonsteroidal anti-inflammatory drugs, sedatives, and barbiturates, not to exceed 72 hours. * Isoniazid in combination with pyridoxine, provided there is no evidence of peripheral neuropathy. * Trimethoprim / sulfamethoxazole. * Amphotericin B (no more than 1 mg/kg for 5 days/week). * Aerosolized ribavirin for bronchiolitis. * Hematopoietic agents. * Other drugs with little nephro-, hepato-, or cytotoxicity. * Nutritional support for HIV wasting syndrome or malnutrition. Patients must have: * HIV infection. * Ongoing stable AZT therapy. Exclusion Criteria Co-existing Condition: Patients with the following symptoms and conditions are excluded: * Disease progression while on AZT, to the extent that the patient meets the criteria for advanced disease protocols. * Known allergy or sensitivity to ddC. * Cardiomyopathy. Concurrent Medication: Excluded: * Biologic modifiers other than IVIG, steroids, or hematopoietic agents. * Investigational medications unless approved by protocol chair. * Medications known to cause pancreatitis (unless ddC is interrupted while these medications are given). Patients with the following prior conditions are excluded: * History of intolerance or toxicity to AZT. * History of symptomatic pancreatitis. * History of peripheral neuropathy or abnormal nerve conduction velocity test. Prior Medication: Excluded: * Antiretroviral agents other than AZT within 2 weeks of study entry. Required: * Ongoing stable AZT therapy for more than 6 weeks duration.