Inclusion Criteria

Concurrent Medication:

Required:

• Chemoprophylaxis for Pneumocystis carinii pneumonia (for patients with a CD4+ cell count less than or equal to 200 cells/mm3.

Allowed:

• Topical and/or oral antifungal agents.
• Treatment, maintenance or chemoprophylaxis with approved agents for opportunistic infections.
• Antibiotics.
• Systemic corticosteroid use for 21 days or less.
• Recombinant erythropoietin (rEPO) and granulocyte-colony stimulating factor (G-CSF, filgrastim).
• Regularly prescribed medications such as antipyretics, analgesics, allergy medications, antidepressants, sleep medications, oral contraceptives (not as a sole form of contraception), megestrol acetate, and testosterone.
• Alternative therapies such as vitamins, acupuncture, and visualization techniques.

[AS PER AMENDMENT 2/27/98:

• Current use of triple therapy with amprenavir/3TC/ZDV (or d4T) for Arm A patients.
• Current use of quadruple therapy with IDV/NVP/3TC/d4T for Arm B patients.]

Patients must have:

• HIV-positive status.
• Successful response to treatment in ACTG 347 as measured by HIV RNA less than 500 copies/ml (Arm A) OR unsuccessful response to treatment in ACTG 347 or another regimen containing amprenavir OR an increase in plasma HIV RNA above the nadir value to greater than 5,000 copies/ml or by at least one log10 at any time (Arm B) OR intolerance to a regimen containing amprenavir.
• Consent for patients less than 18 years of age.

[AS PER AMENDMENT 2/27/98:

Arm A patients must have:

• HIV RNA less than 500 copies/ml on at least one occasion within 60 days of entry while previously enrolled in ACTG 347 and in one of the following categories: currently receiving amprenavir/3TC/ZDV (or d4T) or randomized to monotherapy arm of ACTG 347 and received open-label amprenavir/3TC/ZDV (or d4T).

Arm B patients must have:

• Failed prior amprenavir therapy, whether on ACTG 347 or not, i.e., HIV RNA greater than or equal to 500 copies/ml after at least 16 weeks of amprenavir and confirmed within 1-6 weeks OR treatment failure that mandated early permanent discontinuation of randomized ACTG 347 study drugs and defined as HIV RNA of at least one log 10 above the nadir (to at least 5,000 copies/ml) or HIV RNA level above the baseline value before 16 weeks of amprenavir and confirmed within 1-6 weeks.
• Initially randomized to triple therapy arm of ACTG 347 with two plasma HIV-1 RNA values of at least 500 copies/ml taken within 60 days prior to study entry and at least 1-6 weeks apart or initially receive open-label amprenavir/3TC/ZDV (or d4T) and with two HIV RNA levels of at least 500 copies/ml, regardless of duration of treatment with amprenavir/3TC/ZDV (or d4T).
• Documented intolerance to any of the reverse transcriptase inhibitors or attempted nevirapine therapy allowed. Arm C patients must have:
• Previously enrolled on ACTG 347 and elected to receive a treatment regimen other than amprenavir/3TC/ZDV (or d4T) or IDV/NVP/3TC/d4T.]

Prior Medication: Required:

Amprenavir therapy [AS PER AMENDMENT 2/27/98:

• amprenavir therapy (Arm A and B patients only)].

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or symptoms are excluded:

Arm A:

• Inability to tolerate amprenavir, ZDV, or 3TC.

Arm B:

• Inability to tolerate d4T, NVP, or 3TC.
• Active infection requiring acute treatment within 14 days prior to study entry.
• Malignancy that requires systemic therapy (patients with minimal Kaposi's sarcoma are not excluded provided they do not require systemic therapy).

[AS PER AMENDMENT 2/27/98:

Patients with the following conditions or symptoms are excluded: Arm A:

• Any detection of plasma HIV RNA greater than 500 copies/ml after subject has switched to triple therapy for at least 16 weeks.
• Inability to tolerate amprenavir, ZDV (or d4T), or 3TC.
• Malignancy that requires systemic therapy (minimal Kaposi's sarcoma allowed provided systemic therapy is not required) Arm A and B patients only.]

Concurrent Medication:

Excluded:

• Non-protocol-specified antiretroviral agents.
• Immunomodulators that affect immunologic or virologic indices, such as systemic corticosteroids (more than 21 days), thalidomide, or cytokines.
• Concomitant use of rifabutin and/or rifampin.
• Investigational drugs without specific approval.
• Systemic cytotoxic chemotherapy.
• Oral astemizole, carbamazepine, dexamethasone, ketoconazole, itraconazole, phenobarbital, phenytoin, terfenadine, cisapride, triazolam, terfenadine, astemizole, and midazolam.

Prior Medication:

[AS PER AMENDMENT 2/27/98: Excluded:

• Prior protease inhibitor therapy except amprenavir (Arm A patients).
• Prior protease inhibitor therapy except amprenavir and IDV (Arm B patients).

Excluded within 14 days prior to entry:

• Investigational drugs or immunomodulators (except amprenavir) without specific consent of protocol chair(s) (Arm A patients).
• Immunomodulators that affect immunologic or virologic indices, such as systemic corticosteroids, thalidomide or cytokines, unless approved by protocol chair(s) (Arm B patients).
• Oral astemizole, carbamazepine, dexamethasone, ketoconazole, itraconazole, phenobarbital, phenytoin, terfenadine, cisapride, triazolam, midazolam, ergot alkaloids, or drugs containing derivatives of ergot alkaloids.]