Abstract The oral bioavailability of 3 different dosage forms of sulpiride (Dogmatil), as measured by total 48-h urinary excretion, was studied in 6 healthy male volunteers. Administration of 200 mg of the drug as capsules, tablets and syrup resulted in mean absorptions of 31%, 26% and 20%, respectively. The bioavailability from the syrup was significantly less (ANOVA, P < 0.05) than that from capsules. Coadministration of food or an anticholinergic drug, propantheline bromide, with the syrup increased the mean bioavailbility of the drug to about 26%. The results suggest that the delay in gastric emptying and intestinal transit time due to food or propantheline bromide allows for a better site-specific absorption of sulpiride from the intestine.