ORIGINAL ARTICLE Effects of the H 2 -receptor antagonist ranitidine on gastric motor function after a liquid meal in healthy humans

Objective. Studies on animals have shown that histamine may be involved in the regulation of gastrointestinal smooth muscle tone. However, the role of histamine in the regulation of human gastric motor function is not clear. This study examined the effect of ranitidine, an H2-receptor antagonist, on gastric volume and gastric emptying after a liquid meal in healthy humans. Material and methods. Twelve healthy volunteers participated in a randomized crossover study with 50 mg ranitidine as a bolus intravenously versus no medication. Gastric volume at baseline was determined with single photon emission computed tomography (SPECT) after intravenous injection of 99 m Tc-pertechnetate. After ingestion of a 600-mL liquid meal radiolabelled with 111 Indiethylenetriaminepentaacetic acid, dual-isotope technique with SPECT and planar imaging assessed gastric volume as well as gastric emptying. Results. Ranitidine did not change gastric volume before the meal, nor at 0 h or 1 h after it. Furthermore, ranitidine did not influence gastric retention of meal components after 0.5 h and 1 h. Conclusions. Intravenous bolus injection of 50 mg ranitidine does not modify gastric volume or gastric emptying after a 600 mL liquid meal in healthy humans.