A Study to Evaluate the Effect of Cimetidine on CD4 Lymphocyte Counts in HIV Infection

Inclusion Criteria: Concurrent Medication: Allowed: All FDA-approved medications, antiretrovirals, and PCP prophylaxis drugs, with the exception of warfarin (Coumadin). Other self-prescribed medications available either over the counter or through buyer's clubs. Patients must have: HIV positivity. NOTE: Patients on an antiviral or immunomodulating drug must have received it for at least 2 months and have no intention to make clinical or therapeutic changes in the first 8 weeks (such as adding a new agent or discontinuing effective viral suppressive therapy) that may interfere with the study. NOTE: Patients who become pregnant after enrollment will be permitted to continue on study drug but must sign an additional informed consent indicating their awareness of the issues in taking a drug with limited safety data during pregnancy. Prior Medication: Allowed: Antiviral and immunomodulating drugs, provided patient has been on such therapy for at least 2 months prior to study entry. Exclusion Criteria: Co-existing Condition: Patients with the following symptoms or conditions are excluded: Known intolerance or hypersensitivity to cimetidine. Evidence of active opportunistic infection or malignancy requiring high-dose systemic chemotherapy. Any symptoms suggestive of concurrent illness that are not attributable to overall impairment by HIV or are not diagnosable based on the available evidence. Inability to swallow tablets (gastric feeding tubes are allowed). Not willing to comply with visit schedule and study procedures. Concurrent Medication: Excluded: Warfarin (Coumadin). Prior Medication: Excluded within 4 weeks prior to study entry: cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), and nizatidine (Axid).