Intermittent Foscarnet Therapy for Human Immunodeficiency Virus Infection in Patients Receiving Long-Term Zidovudine Therapy

Inclusion Criteria Concurrent Medication: Allowed: Medication necessary for the patient's welfare at the discretion of the investigator. Patients must have the following: * Received zidovudine (AZT) 200 mg every 4 hours (q4h) continuously for 8 - 16 weeks without Grade 3 or higher toxicity. * Detectable p24 antigen in serum on at least 2 occasions during the prestudy period. All serum p24 antigen concentrations measured during the prestudy period must be at least twice the concentration cutoff value of the assay. * Capability of giving informed consent. * Per amendment of 890721, patients must enter the study period by September 30, 1989. Exclusion Criteria Co-existing Condition: Patients with the following will be excluded: * A history of hypersensitivity reaction to foscarnet or zidovudine (AZT). * History of Grade 3 or 4 toxicity with AZT. * Current Grade 2 or higher AZT toxicity. * Osteomalacia, neoplasm metastatic to bone, or other known bone disease. * Active opportunistic infection requiring myelosuppressive or nephrotoxic therapy. Concurrent Medication: Excluded: * Antimetabolites. * Immunomodulators. * Nephrotoxins. * Antiviral therapy. * Myelosuppressive or nephrotoxic therapy. * Acetaminophen. Patients with the following will be excluded: * A history of hypersensitivity reaction to foscarnet or zidovudine (AZT). * History of Grade 3 or 4 toxicity with AZT. * Current Grade 2 or higher AZT toxicity. * Osteomalacia, neoplasm metastatic to bone, or other known bone disease. * Active opportunistic infection requiring myelosuppressive or nephrotoxic therapy.