A Phase II, Randomized, Double-Blind, Placebo-Controlled Study of the Safety and Antiviral Activity of the Addition of PMPA Prodrug to Combination Antiretroviral Regimens in Treatment-Experienced HIV-Infected Patients

Inclusion Criteria You may be eligible for this study if you: Are HIV-positive. Have an HIV count of 400 - 50,000 copies/ml. Are expected to live for at least 1 year. Have been taking the same anti-HIV drug combination (made up of no more than 3 anti-HIV drugs) for at least 8 weeks prior to study entry. Are at least 18 years old. Agree to use effective methods of birth control during the study. Exclusion Criteria You will not be eligible for this study if you: Have taken medications for certain infections within 15 days prior to study entry. Have a history of cancer, except Kaposi's sarcoma (KS) or skin cancer. Develop a new AIDS-related condition within 30 days of study entry. Have certain serious medical conditions, including severe nausea, vomiting, or other stomach problems that make you unable to take medications by mouth. Have received a vaccine within 30 days prior to study entry. Have taken certain medications, including those that may affect your kidneys. Abuse alcohol or drugs. Are pregnant.