Effectiveness of Early or Delayed Addition of Hydroxyurea to a Three-Drug Anti-HIV Drug Combination Including Didanosine, in Advanced HIV Patients Who Failed a First or Second Anti-HIV Triple-Drug Therapy

Inclusion Criteria Patients may be eligible for this study if they: Are at least 13 years old. Have the signed consent of parent/guardian if under 18 years of age. Are HIV-positive. Have failed 1 or 2 anti-HIV drug combination therapies which had at least 3 anti-HIV drugs each. Have been on stable, triple anti-HIV drug therapy for at least 16 weeks prior to study entry. Have a CD4 count under 300 cells/mm3 within 45 days prior to study entry. Agree not to become pregnant or make anyone else pregnant while on study drugs and for 60 days after stopping drugs. Agree to use 2 methods of birth control while on study drugs and for 60 days after stopping study drugs. Have a negative pregnancy test within 14 days prior to study entry. Exclusion Criteria Patients will not be eligible for this study if they: Received treatment for a serious infection or illness that was completed less than 2 weeks prior to study entry or, if they are still receiving treatment, he/she must have been clinically stable for at least 14 days prior to study entry. Are pregnant or breast-feeding. Are using any drugs that affect the immune system, other than those specified by the study. Received an immunization within 30 days prior to study entry. Have had pancreatitis. Have severe neuropathy (a condition affecting the nervous system). Received granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) within 14 days prior to study entry. Abuse alcohol or drugs. Have any medical condition that would make the patient unable to complete the study. Have used hydroxyurea within 24 weeks prior to study entry. Had hepatitis within 60 days of study entry.