title: Pharmacokinetics and pharmacodynamics of oral and intravenous cimetidine in seriously ill patients.
abstract: This study was done to determine if the pharmacokinetics and gastric pH response of intravenous cimetidine are superior to oral dosing in seriously ill patients. A paired study of intravenous followed by oral liquid cimetidine was given to eight men and two women who were inpatients in a VA Hospital. Treatment was prescribed for either upper gastrointestinal (GI) bleeding or prophylaxis against GI bleeding. All patients received cimetidine 300 mg every 6 hours intravenously on day 1 and orally on day 2. After the fourth dose each day, venous blood samples and gastric pH measurements were taken serially for 6 hours. Peak serum cimetidine concentration was 2.0 +/- 0.5 mg/L for the intravenous dose and 1.5 +/- 0.3 mg/L for the oral dose (P = .001). Area under the curve (AUC) of cimetidine concentration was 3.81 +/- 1.1 mg/hr/L for the intravenous dose and 4.19 +/- 1.22 mg/hr/L for the oral dose (P greater than .30). Bioavailability (AUCpo/AUCiv) was 1.13 +/- 0.25, demonstrating complete oral absorption. The time during a 6-hour dosing interval that the gastric pH remained above 3.0 was 3.3 +/- 2.1 hours for the intravenous dose and 2.5 +/- 2.3 hours for the oral dose, P = .171). The time that the serum cimetidine concentration remained above 0.5 mg/L was 2.0 +/- 0.9 hours for the intravenous dose and 2.7 +/- 1.0 hours for the oral dose (P = .055). We concluded that bioavailability, time that gastric pH is maintained greater 3.0, and time that the serum cimetidine concentration is greater than 0.5 mg/L for intravenous cimetidine are not significantly different from oral cimetidine in seriously ill patients.
authors.affiliation: Section of Gastroenterology, Jerry L. Pettis Memorial Veterans Medical Center, Loma Linda, CA 92357.
authors.forename: W J
authors.initials: WJ
authors.lastname: Sandborn
authors.forename: S C
authors.initials: SC
authors.lastname: Forland
authors.forename: R E
authors.initials: RE
authors.lastname: Cutler
authors.forename: R M
authors.initials: RM
authors.lastname: Strong
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001682:Biological Availability; D002927:Cimetidine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D005260:Female; D005745:Gastric Acidity Determination; D005756:Gastritis / Q000188:drug therapy; D006787:Hospitals, Veterans; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010437:Peptic Ulcer / Q000188:drug therapy; D013997:Time Factors
chemical_list: D002927:Cimetidine