A Study of 1592U89 in HIV-Infected Children

Inclusion Criteria Concurrent Medication: Allowed: * Intravenous immunoglobulin G. * Erythropoietin, granulocyte colony stimulating factor and granulocyte macrophage colony stimulating factor, for the management of hematologic toxicity. Patients must have: * Documented HIV infection. * High risk for disease progression or mortality as defined by either of the following: * Viral load \> 100,000 copies/ml and CD4 cells \< 15% of total lymphocyte count despite at least 4 weeks of therapy with commercially available antiretrovirals or as a result of no therapy due to treatment-limiting toxicity of ZDV, 3TC, and ddI; or HIV-associated encephalopathy refractory to ZDV-containing regimen. * No access to any 1592U89 pediatric study where the patient could qualify for inclusion. * Parent or legal guardian with the ability to understand and provide written consent for the patient to participate in the trial. Study patients over 13 years should also give written informed consent whenever possible. Exclusion Criteria Co-existing Condition: Patients with any of the following symptoms or conditions are excluded: * In the investigator's opinion, the patient is unlikely to comply with the requirements of the study. * Renal failure requiring dialysis. * Hepatic failure evident by Grade 3 or 4 hyperbilirubinemia and AST \> 10 X upper limits of normal. * Life-threatening infection or other chronic disease that may interfere with taking 1592U89 or compromise the patient's safety. Patients with the following prior conditions are excluded: Documented hypersensitivity to 1592U89 or any other nucleoside analogue. See Inclusion - General Criteria.