The purpose of this study is to compare the safety and effectiveness of taking lamivudine (3TC) plus zidovudine (ZDV) plus a protease inhibitor (PI) with taking the 3TC/ZDV combination tablet (Combivir) plus a PI. This study also examines how well patients follow the dosing schedules for these drugs.

Doctors believe that taking Combivir plus a PI may be as effective as taking 3TC plus ZDV plus a PI.

It is hypothesized that a fixed-dose 3TC/ZDV tablet given bid in combination with a protease inhibitor is clinically equivalent in its effect on plasma HIV-1 RNA level to a conventional regimen of 3TC, ZDV, and a protease inhibitor.

Patients are stratified according to their current protease inhibitor therapy and randomized to receive open-label therapy of 1 Combivir tablet bid (Arm II) or an equivalent dose of 3TC and ZDV (Arm I), plus their current protease inhibitor for 16 weeks.

• Drug: Lamivudine/Zidovudine
• Drug: Lamivudine
• Drug: Zidovudine

Inclusion Criteria

Patients must have:

• HIV infection documented by a licensed antibody ELISA assay and confirmed by Western blot, positive HIV blood culture, positive HIV serum antigen, or plasma viremia.
• CD4+ cell count of at least 300 cells/mm3.
• HIV-1 RNA less than 10,000 copies/ml by Roche Amplicor PCR assay.
• CDC Category A or B Classification for HIV infection (no clinical diagnosis of AIDS).
• Compliance with dosing schedule and protocol evaluations.

Prior Medication:

Required:

• 3TC at 150 mg bid, ZDV at 600 mg/day (200 mg tid or 300 mg bid), plus a marketed protease inhibitor (ritonavir, saquinavir, indinavir, or nelfinavir) at its recommended dose for at least 10 weeks.

Allowed:

• Inhaled corticosteroids for the treatment of asthma.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or symptoms are excluded:

• Malabsorption syndromes affecting drug absorption (e.g., Crohn's disease and chronic pancreatitis).
• Enrollment in other investigational protocols.

Concurrent Medication:

Excluded:

• Cytotoxic chemotherapeutic agents.
• Nonnucleoside reverse transcriptase inhibitors.
• Other investigational agents.

Concurrent Treatment:

Excluded:

Radiation therapy.

Prior Medication:

Excluded:

• Cytotoxic chemotherapeutic and immunomodulating agents such as systemic corticosteroids, IF-2, alpha-IFN, beta-IFN, or gamma-IFN (except for inhaled corticosteroids for the treatment of asthma) within 4 weeks of study entry.
• HIV immunotherapeutic vaccine within 3 months of study entry.

Prior Treatment:

Excluded:

Radiation therapy within 4 weeks of study entry.