Concentration effect studies with oral metoclopramide.

1 The effects of single oral doses of 10 mg and 20 mg metoclopramide have been compared to placebo in six normal male volunteers. 2 The drug did not significantly increase the rate of gastric emptying as measured by ethanol absorption. 3 Sedation during the absorption of ethanol was only observed 1 h after the 20 mg oral dose of metoclopramide (P less than 0.05). 4. Akathisia, a central nervous system side effect of metoclopramide, occurred only in subjects who had peak plasma concentrations above 100 ng/ml. 5 It has not been possible to define a concentration-effect relationship for the action of metoclopramide on the stomach and comparison with previous results after intravenous dosing suggests that the route of administration is of major importance in determining the action of this drug.