Elimination of cetirizine following administration of multiple doses to exercised thoroughbred horses.
Cetirizine is an antihistamine used in performance horses for the treatment of hypersensitivity reactions and as such a withdrawal time is necessary prior to competition. The objective of the current study was to describe the disposition and elimination of cetirizine following oral administration in order to provide additional serum concentration data upon which appropriate regulatory recommendations can be established. Nine exercised thoroughbred horses were administered 0.4 mg/kg of cetirizine orally BID for a total of five doses. Blood samples were collected immediately prior to drug administration and at various times postadministration. Serum cetirizine concentrations were determined and selected pharmacokinetic parameters determined. The serum elimination half-life was 5.83 ± 0.841 h. Average serum cetirizine concentrations were still above the LOQ of the assay (0.05 ng/mL) at 48 h (final sample collected) postadministration of the final dose.
K.L. Maddy Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA, USA.|Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
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Knych
K.L. Maddy Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA, USA.|Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
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Stanley
School of Veterinary Medicine, University of California, Davis, CA, USA.
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Arthur
K.L. Maddy Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA, USA.
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McKemie
D000818:Animals; D017332:Cetirizine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D004334:Drug Administration Schedule / Q000662:veterinary; D005260:Female; D006207:Half-Life; D006633:Histamine Antagonists / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D006736:Horses / Q000378:metabolism; D008297:Male; D010805:Physical Conditioning, Animal
D006633:Histamine Antagonists; D017332:Cetirizine