PHARMACOKINETICS OF PENTOBARBITAL IN CAT AND COMPARISONS WITH RABBIT AND MAN

  • 1 January 1977
    • journal article
    • research article
    • Vol. 16  (2) , 375-384
Abstract
In 8 experiments involving 4 cats, doses of 12.5-50 mg of sodium pentobarbital/kg of body weight were administered i.v. and pentobarbital plasma concentrations (from arterial blood) were measured as a function of time. Pharmacokinetic linearity was evidenced by a mean plasma clearance (Clp) of 1.81 ml/kg .times. min), with a coefficient of variation of 16.6%, and a range of 1.51-2.36 for all experiments, and a linear relationship between total area under the curve (AUC) and mg/kg dose in cat no. 4 given doses of 12.5, 25 and 50 mg/kg. The apparent elimination half-life (t1/2).beta., averaged 4.87 h with a coefficient of variation of 40.7% and a range of 1.80-7.52 in all experiments. In cat no. 4 the t1/2 was the same, i.e. a 7.5 h, following the 2 higher doses, but lower i.e., 4.7 h, after the lowest dose. There was also evidence of kinetic nonlinearity in the initial fall-off portions of some of the curves. Results are compared with literature data for both rabbits and man. The order of plasma clearances in units of ml/(kg .times. min) were: rabbit .mchgt. cat > man. For neither the rabbit nor the cat were there any significant correlations between calculated pharmacokinetic parameters and mg/kg doses. This suggested kinetic linearity.

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