The pharmacokinetics, bioequivalence and bioavailability of different formulations of metoclopramide in man.

The pharmacokinetics of 4-amino-5-chloro-N-(2-diethylaminoethyl)-2-methoxybenzamide (metoclopramide, Paspertin) after a single dose of the drug in five different dosage forms: ampoules, tablets, drops, dragées and suppositories, were studied. The clinical investigations were carried out on 10 healthy subjects under carefully controlled conditions. The analysis of metoclopramide in plasma was carried out using reverse-phase high-pressure liquid chromatography. Bioavailabilities between 76 and 79% were determined for the oral application forms and 53% for the rectal application form. Significant differences between maximum plasma levels were found for different individuals. The initial distribution of the drug is very rapid, and the elimination half-lives are comparable for all formulations and ranged from 3.9 and 5.3 h. The apparent volume of distribution is 3.1 l/kg body weight and the total body clearance is 38.4 l/h.