Papich, M. G., E. K. Schooley, et al. (2008). “Pharmacokinetics of cetirizine in healthy cats.” Am J Vet Res 69(5): 670-4.
Cats may suffer from various manifestations of allergic disease affecting body systems such as the skin, respiratory tract, and gastrointestinal tract. Glucocorticoids such as prednisone are effective for treating allergic disease in cats, but may be associated with undesirable adverse effects. Cetirizine (Zyrtec, Pfizer), a second-generation antihistamine, is effective in humans for treatment of allergic symptoms and appears to have less adverse effects than first-generation antihistamines. Although there is anecdotal information about the use of cetirizine in cats, no published pharmacokinetic studies exist and an appropriate oral dose has not been established. In this study, the pharmacokinetic characteristics of cetirizine after oral administration of a single dose was characterized in cats. Each of nine healthy cats was given a single oral dose of 5 mg cetirizine. Blood samples were collected at various time points up to 24 hours after administration and plasma concentrations of cetirizine were analyzed. Cats given this single oral dose of cetirizine had high plasma concentrations compared with those reported in humans, a long halflife, and lack of detectable adverse effects. The results support once daily dosing of cetirizine in cats. Further studies evaluating the therapeutic efficacy of this drug in cats with allergic disease need to be performed, as well as multipledose pharmacokinetic and safety studies. It appears that cetirizine may be a useful alternative to glucocorticoids in cats with allergic disease.
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