The Effectiveness of Three Drug Combinations in HIV-Infected Patients Who Have Taken Zidovudine for More Than 12 Weeks

Inclusion Criteria Concurrent Medication: Required for patients whose CD4 count falls below 200 cells/mm3: * PCP prophylaxis with TMP/SMX, aerosolized pentamidine, or dapsone. Allowed: * Atovaquone, IV pentamidine, trimethoprim-dapsone, clindamycin-primaquine, trimetrexate, or TMP/SMX for acute PCP. * Topical antifungals, clotrimazole, ketoconazole, fluconazole, and amphotericin B for mucosal and esophageal candidiasis. * Itraconazole. * Amphotericin B. * Rifabutin. * Isoniazid. * Pyrazinamide. * Clofazimine. * Clarithromycin. * Azithromycin. * Ethambutol. * Amikacin. * Ciprofloxacin. * Ofloxacin. * Pyrimethamine. * Sulfadiazine. * Clindamycin. * Ganciclovir. * G-CSF. * Acyclovir (up to 1000 mg/day). * Erythropoietin. * Antibiotics for bacterial infections. * Antipyretics. * Analgesics. * Antiemetics. * Rifampin. Concurrent Treatment: Allowed: * Local radiation therapy. Patients must have: * HIV infection. * CD4 count 300-600 cells/mm3. * More than 12 weeks (was 24 weeks, AMENDED 3/31/96) of total prior AZT ( \> 500 mg/day without serious adverse event). Subjects must be actively taking ZDV for at least 4 continuous weeks up to the time of study entry. * No prior or current history of AIDS. * No active opportunistic infection. * Life expectancy of at least 2 years. * Consent of patient and parent or guardian if less than 18 years of age. NOTE: * Protocol is approved for prisoner enrollment. Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: * Malignancy requiring systemic cytotoxic chemotherapy. * Serious underlying medical condition other than HIV that would reduce life expectancy to \< 2 years. Concurrent Medication: Excluded: * Antiretrovirals other than study drugs. * Foscarnet. Patients with the following prior conditions are excluded: * Unexplained temperature \>= 38.5 C for 7 days or chronic diarrhea (\>= three stools daily) for 15 days, if occurring within 30 days prior to study entry. * History of acute or chronic pancreatitis. * History of grade 2 or higher peripheral neuropathy. * History of grade 3 or worse intolerance to 500-600 mg/day AZT. Prior Medication: Excluded: (within 30 days prior to study entry) * Prior ddI, ddC, 3TC or d4T (more than 2 weeks total). * Non-nucleoside reverse transcriptase inhibitor or protease inhibitor. * Biologic response modifiers such as interferon and IL-2. * Other experimental therapy.