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Journal of veterinary internal medicine2020; 35(1); 620-631; doi: 10.1111/jvim.15971

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

Abstract: Omeprazole preparations vary in bioavailability in horses. Objective: 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). Methods: 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: 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.
© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.
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Publication Date: 2020-12-19 PubMed ID: 33340169PubMed Central: PMC7848319DOI: 10.1111/jvim.15971Google Scholar: Lookup
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  • Journal Article
  • Randomized Controlled Trial
  • Veterinary

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigates the bioavailability of two types of omeprazole preparations in horses. The study found both preparations to be associated with reduced gastric ulcer scores and increased gastric fluid pH. This research suggests that omeprazole plasma concentrations and dose don’t directly correlate to drug actions in horses.

Study Design and Approach

  • The study was a prospective, blinded, randomized interventional trial conducted in three parts. Participating subjects were twelve disease-free Standardbred/Thoroughbred mares.
  • The three part study included a bioavailability study, a dose titration study, and a comparative clinical pharmacodynamic study. Each was conducted using a blocked crossover design which redistributes the subjects across different intervention groups to negate possible period effects.

Investigated Omeprazole Preparations

  • The researchers used two types of omeprazole preparations. One was a pre-existing enteric-coated oral omeprazole paste (REF), and the other was a novel, in-feed, enteric-coated dry granule preparation (NOV).
  • Omeprazole is a medication used in horses primarily for the treatment of gastric ulcers. The enteric-coated form of the drug is designed to resist destruction by stomach acid, enhancing its bioavailability.

Results of the Study

  • The values achieved for the concentration of omeprazole in the blood over time (Cmax) and the area under the curve (AUC0-24), used to measure drug exposure, were higher for NOV due to the larger dosage administered.
  • No significant differences between both products were observed in terms of absolute oral bioavailability, which is the proportion of the drug that enters circulation and is able to have an active effect.
  • The treatment with both preparations was associated with reduced gastric squamous ulcer scores and increased pH of gastric fluid, indicating a reduction in stomach acidity.
  • For most pharmacodynamic measures, the two preparations were found to be bioequivalent. The only exception was the percentage of time with pH<4, which despite different dose rates and plasma omeprazole concentrations, did not vary significantly between the two treatments.

Conclusions from the Study

  • Based on the findings of the study, it is concluded that the novel omeprazole product (NOV) is a suitable alternative to the reference product (REF).
  • The study confirms that in horses, the plasma concentrations of omeprazole and the dosage of the drug do not necessarily predict the pharmacodynamic effects of the drug, i.e., its therapeutic effects.

Cite This Article

APA
Wise JC, Hughes KJ, Edwards S, Jacobson GA, Narkowicz CK, Raidal SL. (2020). Pharmacokinetic and pharmacodynamic effects of 2 registered omeprazole preparations and varying dose rates in horses. J Vet Intern Med, 35(1), 620-631. https://doi.org/10.1111/jvim.15971

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 35
Issue: 1
Pages: 620-631

Researcher Affiliations

Wise, Jessica C
  • School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
Hughes, Kristopher J
  • School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
Edwards, Scott
  • School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
Jacobson, Glenn A
  • School of Pharmacy and Pharmacology, University of Tasmania, Hobart, Tasmania, Australia.
Narkowicz, Christian K
  • School of Pharmacy and Pharmacology, University of Tasmania, Hobart, Tasmania, Australia.
Raidal, Sharanne L
  • School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia.

MeSH Terms

  • Administration, Oral
  • Animals
  • Anti-Ulcer Agents / pharmacology
  • Anti-Ulcer Agents / therapeutic use
  • Cross-Over Studies
  • Female
  • Horse Diseases / drug therapy
  • Horses
  • Omeprazole / pharmacology
  • Omeprazole / therapeutic use
  • Prospective Studies
  • Stomach Ulcer / drug therapy
  • Stomach Ulcer / veterinary

Grant Funding

  • Equestra Pty Ltd

Conflict of Interest Statement

The funder Equestra Pty Ltd did not influence the design or conduct of the study, assessment of the data, or writing of the manuscript. The authors have no conflicts of interest.

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Citations

This article has been cited 3 times.
  1. Hodgson E, Thirouin M, Narayanan P, Romano TR, Wise J, Bond S. A novel placement method of a calibration-free pH capsule for continuous wireless measurement of intragastric pH in horses. J Vet Intern Med 2025 Jan-Feb;39(1):e17273.
    doi: 10.1111/jvim.17273pubmed: 39715411google scholar: lookup
  2. Williams Louie E, Nieto J, Wensley F, Morgan JM, Finno CJ, Berryhill EH. Efficacy of the oral supplement, Equine Omega Complete, for the prevention of gastric ulcers and alpha-tocopherol supplementation in horses. J Vet Intern Med 2023 Nov-Dec;37(6):2529-2534.
    doi: 10.1111/jvim.16877pubmed: 37775973google scholar: lookup
  3. Hewetson M, Tallon R. Equine Squamous Gastric Disease: Prevalence, Impact and Management. Vet Med (Auckl) 2021;12:381-399.
    doi: 10.2147/VMRR.S235258pubmed: 35004264google scholar: lookup
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