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143067-Pharmacokinetic and pharmacodynamic effects of 2 registered omeprazole preparations and varying dose rates in horses.pdf (1.59 MB)

Pharmacokinetic and pharmacodynamic effects of 2 registered omeprazole preparations and varying dose rates in horses

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posted on 2023-05-20, 21:27 authored by Wise, JC, Hughes, KJ, Edwards, S, Glenn JacobsonGlenn Jacobson, Christian NarkowiczChristian Narkowicz, Raidal, SL
Background: Omeprazole preparations vary in bioavailability in horses.

Hypothesis/Objectives: To characterize the pharmacokinetics and pharmacodynamics of an existing enteric-coated oral omeprazole paste (REF) and a novel, in-feed, enteric-coated dry granule preparation (NOV).

Animals: Twelve Standardbred/Thoroughbred mares free from clinical disease.

Methods: A prospective, blinded randomized interventional study was trial, conducted in 3 parts: (a) bioavailability study, (b) dose titration study, and (c) comparative clinical pharmacodynamic study, each using a blocked crossover design.

Results: Consistent with the larger dose administered, Cmax (median, 1032 ng/mL; range, 576-1766) and AUC0-24 (median, 63.9 μg/mL*min; range, 42.4-152.4) were greater after single oral administration of NOV than REF (282.7 ng/mL; range, 94.8-390.2, and 319 23.8 μg/mL*min; range, 8.2-42.3, respectively; both P = .004). No differences were observed between products for absolute oral bioavailability (NOV 55% range, 15-88; REF 17% range, 10-77; P = .25). Treatment with both preparations was associated with reduced gastric squamous ulcer scores and increased pH of gastric fluid. Bioequivalence was demonstrated for pharmacodynamic measures with the exception of % time pH <4, despite differences in dose rate and subsequent plasma omeprazole concentrations.

Conclusions and Clinical Importance: The findings of this study indicate that the NOV product would be a suitable alternative to the reference product, and confirm that plasma concentrations of omeprazole and omeprazole dose do not predict drug pharmacodynamics in horses.


Equestra Pty Ltd


Publication title

Journal of Veterinary Internal Medicine








School of Pharmacy and Pharmacology


Amer Coll Veterinary Internal Medicine

Place of publication

7175 W Jefferson Ave, Ste 2125, Lakewood, USA, Co, 80235

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© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License, ( which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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Animal welfare

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