Inclusion Criteria

Concurrent Medication:

Allowed:

• PCP prophylaxis with aerosolized pentamidine, trimethoprim / sulfamethoxazole or dapsone.
• Clotrimazole troches or nystatin oral suspension for oral candidiasis.
• Acyclovir (up to 1000 mg/day) for herpes lesions.

Patients must have:

• HIV infection documented by serologic tests or HIV culture OR prior diagnosis of AIDS by established CDC criteria.
• CD4 counts = or < 500 cells/mm3 on two evaluations.

Part II only:

• No prior therapy with antiretroviral or immunomodulating agents (e.g., AZT, ddI, ddC, interferon).

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms and conditions are excluded:

• Acute medical problems at time of study entry (including active opportunistic infections such as active cryptococcosis, Pneumocystis carinii, herpes zoster, histoplasmosis, or CMV, or nonopportunistic diseases including liver disease, renal disease, orthostatic hypotension, hypertension, lymphoma).
• Current diagnosis of malignancy for which systemic therapy would be required during the study.

Concurrent Medication:

Excluded:

• Any other investigational drugs.
• Phenobarbital, phenytoin, ketoconazole, rifampin, cimetidine, beta blockers, chronic anti-acid therapy, antiarrhythmic agents or other medications known to affect cardiac conduction or seizure threshold.
• Cytotoxic chemotherapy.

Patients with the following prior conditions are excluded:

• History of cardiovascular disease including conduction disturbances, arrhythmias, atherosclerotic heart disease, or valvular heart disease.
• History of CNS disease such as seizure disorder, AIDS Dementia Complex, Progressive Multifocal Leukoencephalopathy, or any other active neurological disorder.
• History of active or chronic gastrointestinal disorders such as chronic diarrhea (> 4 weeks duration), constipation, unexplained abdominal pain (such as irritable bowel syndrome), or other GI motility disorders.
• History of hypercholesterolemia requiring medication or serum cholesterol = or > 300.

Part I patients only:

• History of inability to tolerate zidovudine (200 mg q 8 hours).

Part III patients only:

• History of pancreatitis or > grade 2 peripheral neuropathy.

Prior Medication:

Excluded:

• Cytotoxic chemotherapy within 1 month prior to study entry.

Part II only:

• prior therapy with antiretroviral or immunomodulatory agents (including but not limited to AZT, ddI, ddC, and interferon).

Current use of alcohol or illicit drugs.