Inclusion Criteria

Concurrent Medication:

Required:

• Patients completing ACTG 306 who remain on blinded therapy through the extension period or
• Patients on stable (6 months or greater) ddI/3TC or d4T/3TC combination therapy who have plasma HIV-1 levels higher than 500 copies/ml by the Amplicor HIV-1 Monitor Assay.

Allowed following contact with Protocol Pharmacologist:

• Diltiazem, nifedipine, phenytoin, and warfarin.

Patients must have:

• Absolute CD4 count of 200 cells/mm3 or greater.
• HIV-1 RNA levels greater than 500 copies/ml by the Amplicor HIV-1 Monitor assay. NOTE:
• This is a requirement for those receiving study medication. [AS PER AMENDMENT 12/19/97:
• HIV-1 infection must be documented by any licensed ELISA test kit and confirmed by either Western blot, HIV culture, HIV antigen, plasma HIV RNA, or a second antibody test by a method other than ELISA at any time prior to entry.]
• Signed, informed consent from a parent or legal guardian for patients under 18 years of age.
• Life expectancy of at least 24 weeks.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Unexplained temperature of 38.5 C or higher for 7 consecutive days, or chronic diarrhea defined as more than 3 liquid stools per day persisting for 15 days, within 30 days prior to study entry.
• Proven or suspected acute hepatitis within 30 days prior to study entry.
• Malignancy that requires systemic chemotherapy. NOTE:Patients with minimal Kaposi's sarcoma (KS) fewer than 5 cutaneous lesions and no visceral disease or tumor-associated edema) are allowed to enroll provided that they do not require systemic therapy.

Concurrent Medication:

Excluded:

• Concurrent ZDV (for patients other than those rolling over from ACTG 306).
• Any experimental antiretroviral agents or other experimental therapies.
• Acute therapy for an infection or other medical illnesses within 14 days prior to study entry.
• Recombinant erythropoietin (rEPO), G-CSF, or GM-CSF within 30 days prior to study entry.
• Interferons, interleukins, or HIV vaccines within 30 days prior to study entry.
• Rifampin, rifabutin, cisapride, triazolam, midazolam, terfenadine, astemizole, or loratadine, within 14 days prior to study entry.

Patients with the following prior conditions are excluded:

• History of acute or chronic pancreatitis.
• History of Grade 2 or higher bilateral peripheral neuropathy. [AS PER AMENDMENT 12/19/97: Patients with Grade 2 or 3 peripheral neuropathy due to current use of ddI/3TC or d4T/3TC and who have a screening viral load above 500 copies/ml are eligible as they will be randomized to a regimen that does not contain an agent associated with peripheral neuropathy toxicity.]

Prior Medication:

Excluded:

• Prior NNRTI or protease inhibitor therapy.
• Prior ZDV (for patients other than those rolling over from ACTG 306).
• Previous induction or maintenance therapy with foscarnet.