Evaluation of Patients Who Have Not Had Success With Zidovudine

Inclusion Criteria Concurrent Medication: Allowed: Chemoprophylaxis against Pneumocystis carinii pneumonia (PCP), Mycobacterium tuberculosis, or Herpes simplex virus, or against other opportunistic infections as indicated. Corticosteroids for no longer than 21 days (only as part of PCP therapy). Erythropoietin and G-CSF. Patients must have: Documented HIV-seropositivity. CD4 count 100 - 300 cells/mm3. Prior continuous AZT dose = or > 300 mg/day for 1 year or longer. Prior Medication: Required: AZT for at least 1 year prior to study entry. Exclusion Criteria Co-existing Condition: Patients with the following symptoms and conditions are excluded: Medical contraindication or is considered noncompliant in the opinion of the investigator. Peripheral neuropathy = or > grade 2. Concurrent Medication: Excluded: Anti-HIV agents other than study drugs. Biologic response modifiers (other than erythropoietin or G-CSF). Systemic cytotoxic chemotherapy. Regularly prescribed medications (such as antipyretics, analgesics, allergy medications) that are associated with an increased risk of pancreatitis, peripheral neuropathy, or bone marrow suppression. Concurrent Treatment: Excluded: Radiation therapy. Patients with the following prior conditions are excluded: History of acute or chronic pancreatitis, gout, or uric acid nephropathy. Prior Medication: Excluded: Other antiretrovirals besides AZT. ddI or ddC for more than 30 days within the past year or any time within 3 months prior to study entry. Acute therapy for an infection or other medical illness within 14 days prior to study entry.