A Double-Blind, Randomized, Multicenter Trial to Evaluate the Safety and Efficacy of the Combination of 1592U89/Zidovudine (ZDV)/Lamivudine (3TC) Versus the Combination of Zidovudine (ZDV)/Lamivudine (3TC) in HIV-1 Therapy-Experienced Pediatric Patients.

Inclusion Criteria

Inclusion Criteria

Concurrent Medication:

Allowed:

- Intravenous immunoglobulin G, erythropoietin, G-CSF and GM-CSF.

- Opportunistic infection prophylaxis.

Patients must have:

- HIV-1 infection documented by:

< 18 months of age:

- one positive viral test culture and one other positive viral test (culture, PCR, p24
antigen, or Immune Complex Dissociation p24 antigen) on two different specimens.

>= 18 months of age:

- two positive viral tests as stated above, one or both of which may be determined by a
federally documented ELISA and confirmed by Western blot or Indirect Fluorescent
Antibody test.

- Any of the CDC Categories:

- 1, 2, 3, and N, A, B, and C of the 1994 Revised Classification System for HIV
Infection in Children Less than 13 Years of Age.

- CD4+ count >= 15% within 14 days prior to study drug administration.

- No active or ongoing AIDS-defining opportunistic infection that precludes absorption
of study drug or observation of a study parameter.

- Signed, informed consent from parent or legal guardian for patients under 18 years of
age.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or symptoms are excluded:

- Serious bacterial infection that precludes absorption of study drug or observation of
a study parameter.

- Documented hypersensitivity to a nucleoside analog.

- Co-enrollment in certain opportunistic infection protocols is not exclusionary if
approval is obtained.

- Malignancy.

- Life-threatening infection or other chronic disease that may compromise patient
safety.

- Grade 3/4 clinical or laboratory toxicity or current grade 2 or higher pancreatic
amylase or lipase toxicity as defined by the ACTG Toxicity Tables within 14 days
prior to study entry.

Concurrent Medication:

Excluded:

- Other anti-HIV therapy.

- Probenecid.

- Biologic response modifier (unless listed under included concurrent medication) and
megestrol acetate.

- Human growth hormone.

- Immunomodulators and cytotoxic chemotherapeutic agents.

- Systemic corticosteroids > 14 days without approval.

- Investigational agents.

Concurrent Treatment:

Excluded:

Radiation therapy.

Patients with the following prior conditions are excluded:

- History of clinically relevant pancreatitis or hepatitis within the past 6 months.

- Participation in a vaccine trial.

Prior Medication:

Excluded:

- Protease inhibitor therapy within 2 weeks prior to randomization.

- Interleukins or interferons within 30 days prior to study drug administration.

- Investigational drugs within 14 days prior to randomization.

- HIV vaccine dose within past 30 days.

Required:

> 12 weeks prior antiretroviral therapy and unchanged therapy 12 weeks prior to screening.