Pharmacokinetics of Intragastric Ursodeoxycholic Acid and Its Impact on Bile Acid Profiles in Horses.
Abstract: Ursodeoxycholic acid (UDCA), a secondary bile acid (BA) with therapeutic applications, is standard therapy for cholestatic hepatopathies in humans. In recent years, its use has been increasingly explored in equine medicine for similar indications. Pharmacokinetic data for UDCA in horses are currently lacking. This study aimed to describe the pharmacokinetic parameters following a single intragastric administration of 15 mg/kg in nine healthy, fasted horses and to characterize the changes in their BA profiles. Plasma concentrations of UDCA were measured at specific time points using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pharmacokinetic analysis revealed a sharp increase in plasma concentrations within the first 1-3 h, with peak concentrations (Tmax) occurring at 2.44 ± 1.3 h. Plasma concentrations decreased significantly in most horses at 24 h, with negligible concentrations detected at 48-72 h. Mean half-life was calculated at 7.99 ± 2.25 h, and the dose interval estimate mean was 24.29 h. BA profile analysis demonstrated an increase in total BA concentrations post-administration, with a notable rise in the percentage of UDCA relative to other BAs. Based on these findings, we conclude that the intragastric dose of 15 mg/kg every 24 h is appropriate for horses. Clinicians should be aware that, post-administration, total BA concentrations are likely to increase within hours, with UDCA becoming the predominant BA.
© 2026 John Wiley & Sons Ltd.
Publication Date: 2026-01-26 PubMed ID: 41588271DOI: 10.1111/jvp.70048Google Scholar: Lookup
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- Journal Article
Summary
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Overview
- This study investigated how ursodeoxycholic acid (UDCA), a bile acid used to treat liver conditions, is absorbed and processed in horses following oral administration.
- It also examined how UDCA administration changes the overall bile acid composition in the horses’ blood.
Background
- Ursodeoxycholic acid (UDCA) is a secondary bile acid commonly used in human medicine to treat cholestatic liver diseases.
- Its application in veterinary medicine, particularly in horses, is growing due to presumed similar therapeutic effects.
- However, before this study, there was limited information on how UDCA behaves pharmacokinetically in horses—i.e., its absorption, distribution, metabolism, and elimination.
- Understanding the pharmacokinetics is crucial for determining appropriate dosing regimens in horses.
Study Design
- The study involved nine healthy, fasted horses who were given a single intragastric dose of UDCA at 15 mg/kg.
- Blood samples were collected at various time points after administration to measure plasma concentrations of UDCA and assess changes in the bile acid profile.
- The measurements were performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a precise analytical technique for quantifying bile acids.
Pharmacokinetic Findings
- After administration, plasma UDCA concentrations increased sharply within 1 to 3 hours, indicating rapid absorption from the gastrointestinal tract.
- The time to reach peak concentration (Tmax) averaged 2.44 ± 1.3 hours.
- Plasma levels of UDCA significantly declined by 24 hours post-dose, and were almost undetectable at 48 to 72 hours, showing elimination over this period.
- The mean plasma half-life of UDCA was approximately 7.99 ± 2.25 hours, which informs how long the drug remains active in the bloodstream.
- The estimated dosing interval based on these data was roughly 24.29 hours, supporting a once-daily dosing schedule.
Bile Acid Profile Changes
- In addition to measuring UDCA itself, the study characterized the overall bile acid profile in plasma post-administration.
- Total bile acid concentrations increased following UDCA dosing, suggesting an overall impact on bile acid metabolism.
- Notably, the proportion of UDCA relative to other bile acids also increased, indicating UDCA became the dominant bile acid during this period.
Conclusions and Clinical Implications
- The data support the use of 15 mg/kg UDCA given intragastrically every 24 hours in horses as an appropriate dosing interval and amount.
- Clinicians should anticipate that plasma bile acids will rise after dosing, with UDCA predominating the profile.
- This pharmacokinetic profile aids in optimizing therapeutic strategies for equine liver diseases where UDCA might be beneficial.
- Further studies may be warranted to investigate the effect of repeated dosing and to explore efficacy in horses with liver pathologies.
Cite This Article
APA
Macias A, Delvescovo B, Donaldson SF, Divers TJ, Donnelly CG.
(2026).
Pharmacokinetics of Intragastric Ursodeoxycholic Acid and Its Impact on Bile Acid Profiles in Horses.
J Vet Pharmacol Ther.
https://doi.org/10.1111/jvp.70048 Publication
Researcher Affiliations
- Department of Clinical Sciences, Cornell University, Ithaca, New York, USA.
- Department of Clinical Sciences, Cornell University, Ithaca, New York, USA.
- Department of Clinical Sciences, Cornell University, Ithaca, New York, USA.
- Department of Clinical Sciences, Cornell University, Ithaca, New York, USA.
- Department of Clinical Sciences, Cornell University, Ithaca, New York, USA.
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