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Research article2003Peer reviewed

Pharmacokinetics and pharmacodynamics of clemastine in healthy horses

Törneke, K; Ingvast-Larsson, C; Pettersson, K; Bergvall, K; Hedeland, M; Bondesson, U; Broström, H

Abstract

Clemastine is an H-1 antagonist used in certain allergic disorders in humans and tentatively also in horses, although the pharmacology of the drug in this species has not yet been investigated. In the present study we determined basic pharmacokinetic parameters and compared the effect of the drug measured as inhibition of histamine-induced cutaneous wheal formation in six horses. The most prominent feature of drug disposition after intravenous dose of 50 mug/kg bw was a very rapid initial decline in plasma concentration, followed by a terminal phase with a half-life of 5.4 h. The volume of distribution was large, V (ss) = 3.8 L/kg, and the total body clearance 0.79 L/h kg. Notably, oral bioavailability was only 3.4%. There was a strong relationship between plasma concentrations and effect. The effect maximum (measured as reduction in histamine-induced cutaneous wheal formation) was 65% (compared with controls where saline was injected) and the effect duration after i.v. dose was approximately 5 h. The effect after oral dose of 200 mug/kg was minor. The results indicate that clemastine is not appropriate for oral administration to horses because of low bioavailability. When using repeated i.v. administration, the drug has to be administered at least three to four times daily to maintain therapeutic plasma concentrations because of the short half-life. However, if sufficient plasma concentrations are maintained the drug is efficacious in reducing histamine-induced wheal formations.

Keywords

clemastine; horse

Published in

Journal of Veterinary Pharmacology and Therapeutics
2003, volume: 26, number: 2, pages: 151-157
Publisher: Blackwell Publishing Ltd

SLU Authors

  • Broström, Hans

    • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    • Department of Large Animal Clinical Sciences, Swedish University of Agricultural Sciences

  • Törneke, Karolina

    • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences

  • Ingvast Larsson, Carina

    • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences

  • Bergvall, Kerstin

    • Department of Small Animal Clinical Sciences, Swedish University of Agricultural Sciences

UKÄ Subject classification

Pharmacology and Toxicology
Other Veterinary Science

Publication identifier

  • DOI: https://doi.org/10.1046/j.1365-2885.2003.00460.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/1691