Inclusion Criteria

Concurrent Medication:

Required:

• PCP prophylaxis.

Allowed:

• Erythropoietin.
• Prophylaxis for MAI or fungal infections.
• Antibiotics.
• Over-the-counter, alternative, or regularly prescribed drugs.
• Steroids, if for < 21 days.

Concurrent Treatment:

Allowed:

• Radiation therapy for cutaneous Kaposi's sarcoma.

Patients must have:

• HIV infection.
• CD4 count <= 50 cells/mm3.
• Prior nucleoside monotherapy for at least 6 months.
• Life expectancy of at least 6 months.

Prior Medication: Required:

• Nucleoside monotherapy for at least 6 months. Active alcohol or drug abuse.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Severe peripheral neuropathy.
• Psychological or emotional problems sufficient to prevent study compliance.

Concurrent Medication:

Excluded:

• Systemic chemotherapy for malignancy.
• Acute or induction therapy for opportunistic infection.

Patients with the following prior conditions are excluded:

• History of acute or chronic pancreatitis.
• Grade 3 or greater toxicity to AZT, ddI, or ddC on two or more occasions.

Prior Medication:

Excluded:

• Non-study nucleosides or biologic response modifiers within 7 days prior to study entry.
• Acute therapy for opportunistic process within 14 days prior to study entry.
• Acute systemic therapy for other medical conditions within 14 days prior to study entry.