A Randomized, Double-Blind, Four-Arm Study Comparing Combination Nucleoside, Alternating Nucleoside, and Triple-Drug Therapy for the Treatment of Advanced HIV Disease (CD4 <= 50/mm3)

Inclusion Criteria Concurrent Medication: Required: * PCP prophylaxis. Allowed: * Erythropoietin maintenance. * G-CSF and GM-CSF. * Prophylaxis for Mycobacterium avium intracellulare. * Antifungal prophylaxis or treatment with specific drugs. * Maintenance therapy for opportunistic infection. * Over-the-counter medications or alternative therapies such as vitamins and herbs. * Antibiotics as clinically indicated. * Steroids for \< 21 days for acute problems. * Antipyretics, analgesics, allergy medication, antidepressants, sleep medications, oral contraceptives, or other appropriate medications. Concurrent Treatment: Allowed: * Radiation therapy for cutaneous Kaposi's sarcoma. * Acupuncture. Patients must have: * Documented HIV infection. * CD4 count \<= 50 cells/mm3. * Either no prior nucleoside therapy OR a history of prior nucleoside therapy in the absence of high-grade intolerance. * Life expectancy of at least 6 months. * Consent of parent or guardian if \< 18 years of age. * Normal chest x-ray at baseline or within 6 months prior to study entry in the absence of new pulmonary or cardiac symptoms (per 12/28/94 amendment). NOTE: * Patients who withdrew from protocol ACTG 193 therapy prior to activation of ACTG 193A are not eligible. Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: * Abnormal baseline chest x-ray. * New pulmonary or cardiac symptoms. * Psychological or emotional problems sufficient to prevent compliance with study medication. Concurrent Medication: Excluded: * Systemic chemotherapy for malignancy. * Acute or induction therapy for opportunistic infection. * Antiretroviral drugs other than study drugs. * Biological response modifiers. * Erythromycin, phenytoin, phenobarbital, warfarin, or coumadin. Patients with the following prior conditions are excluded: * History of recurrent grade 3 or greater toxicity to AZT, ddI, or ddC on two or more occasions. * Evidence of active pulmonary disease within 6 months prior to study entry. * History of grade 3 or worse peripheral neuropathy. * History of acute or chronic pancreatitis. Prior Medication: Excluded: * Prior nevirapine. Excluded within 7 days prior to study entry: * Acute therapy for opportunistic infection (maintenance therapy is permitted). * Acute systemic therapy for a nonopportunistic infection or other medical condition. * Antiretroviral drugs other than AZT, ddI, or ddC. * Biological response modifiers. * d4T therapy. * Nucleosides other than those used in the study. * Antibiotics containing clavulanate potassium. Prior Treatment: Excluded: * More than 4 units of blood in a 30-day period. Active alcohol or drug abuse.