The Safety and Effectiveness of Zidovudine Plus Lamivudine, Used With and Without 1592U89, in HIV-1 Infected Children Who Have Taken Anti-HIV-1 Drugs

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.