Evaluation of the effect of ranitidine on gastroduodenal contractile activity and gastric emptying in horses

Omar Maher, Jorge E. Nieto, Scott D. Stanley, Elizabeth Dore, Jack R. Snyder

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Objective - To determine the effect of ranitidine on gastric emptying in horses. Animals - 11 adult horses. Procedures - In vitro, isolated muscle strips from the pyloric antrum and duodenum of 5 horses were suspended in baths and attached to isometric force transducers. Once stable spontaneous contractions were observed, ranitidine or diluent was added at cumulative increasing concentrations. Isometric stress responses were compared. In vivo, 6 horses were assigned to a group in a prospective randomized crossover study design with a wash-out period of 2 weeks between trials. Ranitidine (2.2 mg/kg) or saline (0.9% NaCl) solution was administered IV, and 15 minutes later, acetaminophen (20 mg/kg), diluted in 400 mL of water, was administered via nasogastric tube to evaluate the liquid phase of gastric emptying. Serum acetaminophen concentration was measured at several time points for 3 hours by use of liquid chromatography tandem mass spectrometry. Frequency of defecation was recorded during the 3 hours of the study. Results - Ranitidine increased the contractile activity of the pyloric antrum smooth muscle at a concentration of 10-4M. No significant effect of ranitidine on plasma kinetics of acetaminophen was identified. Frequency of defecation did not differ between groups. Conclusions and Clinical Relevance - Ranitidine did increase gastric motility in vitro, but no effect on liquid phase gastric emptying was identified in healthy horses by use of the acetaminophen absorption model. Results do not support the use of ranitidine to promote gastric emptying.

Original languageEnglish
Pages (from-to)1153-1157
Number of pages5
JournalAmerican Journal of Veterinary Research
Issue number9
StatePublished - Sep 2008

ASJC Scopus subject areas

  • General Veterinary


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