OBJECTIVE: The rationale for the widespread use of intravenous H-2 receptor antagonists (IVH2 RA) in hospitalized patients is not clear. We therefore examined prescribing pat terns and, using strict criteria, determined whether use was appropriate. Cost of administration and potential savings were also determined. METHODS: Data were obtained prospectively on 100 consecutive patients prescribed intravenous ranitidine and retrospectively on patients admitted with gastrointestinal (GI) bleeding. RESULTS: For the prospective study, various indications for prescribing intravenous ranitidine were given, including postoperative patients and patients treated with steroids. Using criteria from published literature 80% of the use was considered inappropriate. Nearly 40% of the doses were given while the patient was tolerating oral intake. Creatinine clearance was impaired in 26% of patients, though only one had dosage reduction. Estimated annual cost of intravenous ranitidine was $317,000. The retrospective study of 86 consecutive patients admitted with GI bleeding revealed that all patients received intravenous ranitidine on admission, none of which was considered appropriate. The final diagnoses were peptic ulcer (49), colonic process (11), esophagitis (seven), gastric erosions (five), esophageal varices (five), Mallory-Weiss tears (four), duodenitis (two), mo diagnosis (three), and jejunal ulcer (one). CONCLUSIONS: Inappropriate use of intravenous ranitidine is common. This includes inappropriate indication, dosage, and duration of use. Large financial benefits could have been obtained if close attention was given to prescribing patterns. (Am J Gastroenterol 1999;94:3473-3477. (C) 1999 by Am. Coll. of Gastroenterology).