title: The effects of dose and diet on the pharmacokinetics of omeprazole in the horse.
abstract: This study aimed to investigate the effect of diet and dose on the pharmacokinetics of omeprazole in the horse. Six horses received two doses (1 and 4 mg/kg) of omeprazole orally once daily for 5 days. Each dose was evaluated during feeding either a high-grain/low-fibre (HG/LF) diet or an ad libitum hay (HAY) diet in a four-way crossover design. Plasma samples were collected for pharmacokinetic analysis on days 1 and 5. Plasma omeprazole concentrations were determined by ultra-high pressure liquid chromatography-mass spectrometry. In horses being fed the HG/LF diet, on day 1, the area under the curve (AUC) and maximal plasma concentration (Cmax) were higher on the 4 mg/kg dose than on the 1 mg/kg dose. The AUC was higher on day 5 compared to day 1 with the 4 mg/kg dose on the HG/LF diet. On days 1 and 5, the AUC and Cmaxwere higher in horses being fed the HG/LF diet and receiving the 4 mg/kg dose than in horses being fed the HAY diet and receiving the 1 mg/kg dose. These findings suggest that both dose and diet may affect pharmacokinetic variables of omeprazole in the horse.
authors.affiliation: School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia.
authors.forename: B W
authors.initials: BW
authors.lastname: Sykes
authors.affiliation: School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Underwood
authors.affiliation: Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: McGowan
authors.affiliation: School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia.
authors.forename: P C
authors.initials: PC
authors.lastname: Mills
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D000897:Anti-Ulcer Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D018592:Cross-Over Studies; D004032:Diet / Q000662:veterinary*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006207:Half-Life; D006736:Horses / Q000097:blood* / Q000378:metabolism; D009853:Omeprazole / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D000897:Anti-Ulcer Agents; D009853:Omeprazole