Use of i.v. cimetidine, ranitidine, and famotidine in 40 hospitals

The drug experiences of 1200 patients receiving i.v. histamine H2-receptor antagonists were studied. Forty hospitals in five southeastern states participated in a drug-use evaluation (DUE). In addition to supplying background information, a pharmacist at each hospital used a standardized form to perform a concurrent review of 30 consecutive adult patients who had been started on i.v. cimetidine, ranitidine, or famotidine. In addition to the patient's age and the prescriber's medical specialty, specific DUE criteria included the reason given in the medical record for use; dosage regimen and adjustments made on the basis of the patient's renal function; other GI drugs taken concurrently; pharmacist intervention; simultaneous use of oral medications; occurrence of adverse events; H2-antagonist use with specified drug products known to affect serum drug concentrations of one or both medications; and use of gastric pH monitoring. Therapy with i.v. H2 antagonists was usually started by internal medicine specialists or surgeons, and most of the evaluated patients received such therapy for prevention of stress-related mucosal damage. According to estimated creatinine clearance, 34% of patients were in need of dosage adjustments, but such adjustments were made in only 49% of these. Forty percent of patients began therapy while taking at least one medication orally, and almost one fourth of patients were receiving an additional drug for the treatment of an acid-peptic or related indication. The occurrence of adverse events was similar for the three H2 antagonists studied. The findings identify several problematic areas in the way H2 antagonists are used in clinical practice.