Pharmacokinetics of the Gastroprokinetic Agent Mosapride Citrate after Single Oral Administration in Horses

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The purpose of this study was to determine the pharmacokinetics and dose proportionality of mosapride citrate, a selective 5-HT₄ agonist, after oral administration in horses. Seven healthy Thoroughbreds were dosed with distilled water and 0.5, 1.0, or 1.5 mg/kg mosapride citrate through a nasogastric tube. Serum mosapride concentrations were measured by a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method. Mosapride showed the C_maxs of 31, 60, and 104 ng/g and AUCs of 178, 357, and 566 ng·hr/g at doses of 0.5, 1.0, 1.5 mg/kg, respectively. The C_maxs and AUCs increased in proportion to the dose, indicating linear pharmacokinetics of mosapride up to 1.5 mg/kg. The pharmacokinetic profiles of mosapride in horses are quite different from that in humans. The average t_1/2 in horses was almost 2 fold longer than that reported in healthy adult humans. Therefore, it is thought that it is suitable to reduce the number of doses a day in horses compared to humans.