Pharmacokinetics of metoclopramide in goats

The pharmacokinetics of a parenteral formulation of metoclopramide (mono‐chloride monohydrate) were determined following single intravenous (i.v.) and intramuscular (i.m.) 0.5‐mg/kg doses to two groups of 4 goats in a crossover design. Mean serum concentrations of metoclopramide following i.v. administration of 0.5 mg/kg declined rapidly from a peak of 277.5 ng/ml at 3 min postdosing to 25 ng/ml at 90 min. Serum concentrations were not detectable by 120 min after drug administration. The curve of serum concentrations vs. time was characteristic of a two‐compartment open model. Mean parameters from analysis of the individual i.v. data gave a biological half‐life of 0.62 h and a volume of distribution of the central compartment of 1.34 I/kg. Serum concentrations of metoclopramide following i.m. administration of 0.5 mg/kg rose rapidly to a peak of 160.9 ng/ml at 15 min post‐dosing and then declined in parallel with the elimination phase of the i.v. study. These data were best described by a two‐compartment open model with first‐order absorption. The mean biological half‐life was 1.04 h. There were no adverse reactions associated with metoclopramide at the 0.5‐mgfkg dose administered by either route.