Assessment of the relative and absolute bioavailability of immediate release and sustained release formulations of metoclopramide. Assessment of the effect of a high-fat meal on the pharmacokinetics of sustained release metoclopramide.In a balanced 4-way crossover study in 16 healthy male volunteers, a sustained release (SR) formulation of metoclopramide was compared with a solution for injection (A) and an immediate release tablet (B). The SR formulation was administered after a fasting period (C) as well as after a high-fat meal (D). A single dose of 30 mg metoclopramide was investigated in each treatment. Metoclopramide concentrations were determined by HPLC.The absolute bioavailability of the sustained release formulation (fasting state) was 58% and thus about 17% lower than the bioavailability of the immediate release formulation. Comparing the treatments C (sustained release, fasting state) and D (sustained release, high-fat meal) no significant influence of food on the absorption of sustained release metoclopramide could be detected.