Pharmacokinetics and effects of cetirizine in horses with insect bite hypersensitivity.

Author(s): Olsen L, Bondesson U, Brostrom H, Olsson U, Mazogi B, Sundqvist M, Tjalve H, Ingvast-Larsson C

Affiliation(s): Division of Pathology, Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden. Lena.Olsen@bvf.slu.se

Publication date & source: 2011-03, Vet J., 187(3):347-51. Epub 2010 Jan 25.

Publication type: Randomized Controlled Trial; Research Support, Non-U.S. Gov't

Horses with insect bite hypersensitivity (IBH) have difficulty in completely avoiding allergens, so effective treatment options are required. A randomised, placebo controlled and double blinded field study was conducted to determine the pharmacokinetics and efficacy in reducing dermatitis of the antihistamine cetirizine given orally at 0.4 mg/kg twice daily for 3 weeks. The influence of protection blankets and stabling were also investigated. The estimated maximum plasma concentration (C(max)) and trough plasma concentration of cetirizine were 135 ng/mL and 18 ng/mL, respectively. There was no difference in dermatitis reduction between the treatment and placebo groups (P = 0.77). The findings indicated that cetirizine was of no apparent benefit in treating IBH at the dose rate tested. The use of blankets and stabling were shown to have favourable influence on the dermatitis (P < 0.05) and may be the preferred options to prevent this condition. Copyright (c) 2010 Elsevier Ltd. All rights reserved.