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Pharmacodynamics of clemastine in healthy horses
Author(s) -
Bergvall K.,
Ingvast Larsson C.,
Broström H.,
Törneke K.
Publication year - 2002
Publication title -
veterinary dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.744
H-Index - 60
eISSN - 1365-3164
pISSN - 0959-4493
DOI - 10.1046/j.1365-3164.2002.00298_20.x
Subject(s) - histamine , medicine , pharmacodynamics , pharmacology , crossover study , bioavailability , intradermal injection , oral administration , saline , pharmacokinetics , anesthesia , immunology , pathology , alternative medicine , placebo
The aim of this study was to evaluate the efficacy of the H 1 ‐receptor inhibitor clemastine (a compound belonging to the first generation of antihistamines) in equine skin after a single intravenous and oral dose. Histamine binds to H 1 ‐receptors involved in pruritus, increased vascular permeability, release of inflammatory mediators and recruitment of inflammatory cells. To counteract these effects antihistamines have classically been used for treatment of allergic hypersensitivity disorders and urticaria in several species including dogs, cats and horses. Six horses received clemastine orally, 200 µg kg −1 , by stomach tube and 50 mg kg −1 as an intravenous infusion in a crossover study with crossover design. The ability to reduce wheal formation after intradermal injection of histamine was evaluated. Intradermal injections of 0.07 mL histamine dihydrochloride (0.1 mg mL −1 ) were given before and at seven time periods ranging from 0.5 to 24 h after clemastine administration. Wheal area was measured 20 min after the injection. Sterile saline (0.07 mL) served as a negative control. There was a marked reduction in wheal size for approximately 6 h after the intravenous administration, indicating that clemastine is distributed to, and effective in inhibiting H 1 ‐receptors in, equine skin. After oral administration the effect was almost negligible, indicating low oral bioavailability of clemastine in the horse. The study was funded by Linnea and Axel Ericsson’s Grant fund at the Veterinary Faculty, Swedish University of Agricultural Sciences.