Abstract

The pharmacokinetics of the histamine HI-antagonist cetirizine and its effect on histamine-induced cutaneous wheal formation were studied in six healthy horses following repeated oral administration. After three consecutive administrations of cetirizine (0.2 mg/kg body weight, bw) every 12 h, the trough plasma concentration of cetirizine was 16 +/- 4 ng/mL (mean +/- SD) and the wheal formation was inhibited by 45 +/- 23%. After four additional administrations of cetirizine (0.4 mg/kg bw) every 12 h, the trough plasma concentration was 48 +/- 15 ng/mL and the wheal formation was inhibited by 68 +/- 11%. The terminal half-life was about 5.8 h. A pharmacokinetic/ pharmacodynamic link model showed that the maximal inhibition of wheal formation was about 95% and the EC(50) about 18 ng/mL. It is concluded that cetirizine in doses of 0.2-0.4 mg/kg bw administered at 12 h intervals exhibits favourable pharmacokinetic and pharmacodynamic properties without causing visible side effects, and the drug may therefore be a useful antihistamine in equine medicine. (C) 2007 Elsevier Ltd. All rights reserved.

Keywords

horse; antihistamine; cetirizine; PK/PD link model

Published in

Veterinary Journal
2008, volume: 177, number: 2, pages: 242-249
Publisher: Elsevier

Authors' information