Effect of cimetidine on basal and postprandial plasma concentrations of cholecystokinin and gastrin in humans.

Cimetidine reduces the appetite and weight in healthy overweight subjects. Gastrointestinal regulatory peptides such as cholecystokinin (CCK) have been proposed to mediate the satiety signal from gut to brain. Therefore, the effect of cimetidine on basal and postprandial plasma concentrations of cholecystokinin and gastrin was studied. After an overnight fast, 12 healthy volunteers were given cimetidine (400 mg) on day 1, breakfast on day 2, and cimetidine 20 min before breakfast on day 3. Plasma concentrations of cholecystokinin and gastrin were measured by radioimmunoassay. Plasma cholecystokinin concentration increased with one major peak observed 30 min and one smaller peak observed 120 min after intake of cimetidine. The meal induced an increase in the plasma concentration of cholecystokinin, while cimetidine prior to the meal elicited a sustained postprandial cholecystokinin response. Cimetidine had no effect on the basal plasma concentration of gastrin. The meal induced an increase in the plasma concentration of gastrin, while cimetidine prior to the meal elicited a sustained postprandial gastrin response. In conclusion, cimetidine increases the basal concentration of plasma cholecystokinin and elicits a sustained postprandial response of both cholecystokinin and gastrin. At least the cholecystokinin response may be one mechanism by which cimetidine reduces the appetite.