A Phase I/II Study of the Safety, Tolerance, and Pharmacokinetics of 9-(2-Phosphonylmethoxyethyl)Adenine ( PMEA; Adefovir ) in Patients With Advanced HIV Disease.

Inclusion Criteria Concurrent Medication: Allowed: * Other antiretroviral therapy IF on a stable dose for at least 4 weeks prior to study entry. * Prophylactic therapy with aerosolized pentamidine, oral trimethoprim/sulfamethoxazole (Bactrim, Septra) or dapsone, and fluconazole or ketoconazole IF on a stable prophylactic regimen for at least 4 weeks prior to study entry. Patients must have: * HIV seropositivity. * Elevated p24 antigen (\> 40 pg/ml). * Mean CD4 count \<= 100 cells/mm3. * Life expectancy of at least 3 months. Prior Medication: Allowed: * Other prior antiretroviral therapy. * Prophylactic therapy with aerosolized pentamidine, oral trimethoprim/sulfamethoxazole (Bactrim, Septra) or dapsone, and fluconazole or ketoconazole. Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: * Inadequate venous access. * Active serious infection (other than HIV infection) requiring parenteral antibiotic therapy. * Clinically significant cardiac disease, including symptoms of ischemia, congestive heart failure, or arrhythmia. * Psychiatric disturbance or illness that may affect compliance. * Malignancy other than Kaposi's sarcoma. Concurrent Medication: Excluded: * Investigational agents other than stavudine (d4T). * Interferon-alpha. * Ganciclovir. * Foscarnet. * Diuretics. * Amphotericin B. * Aminoglycoside antibiotics. * Other nephrotoxic agents. * Acyclovir at doses \>= 2 g/day. Prior Medication: Excluded within 2 weeks prior to study entry: * Investigational agents other than stavudine (d4T). * Interferon-alpha. * Ganciclovir. * Foscarnet. * Diuretics. * Amphotericin B. * Aminoglycoside antibiotics. * Other nephrotoxic agents. Excluded within 4 weeks prior to study entry: * Systemic therapy for Kaposi's sarcoma. Substance abuse.