European Journal of Clinical Pharmacology 2005-05-01

Induction of the metabolism of etizolam by carbamazepine in humans.

S Kondo, T Fukasawa, N Yasui-Furukori, T Aoshima, A Suzuki, Y Inoue, T Tateishi, K Otani

Index: Eur. J. Clin. Pharmacol. 61(3) , 185-8, (2005)

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Abstract

To examine the effect of carbamazepine on the single oral dose pharmacokinetics of etizolam.Eleven healthy male volunteers received carbamazepine 200 mg/day or placebo for 6 days in a double-blind, randomized, crossover manner, and on the sixth day they received a single oral 1-mg dose of etizolam. Blood samplings and evaluation of psychomotor function by the Digit Symbol Substitution Test and Stanford Sleepiness Scale were conducted up to 24 h after etizolam dosing. Plasma concentration of etizolam was measured using high-performance liquid chromatography.Carbamazepine treatment significantly decreased the peak plasma concentration (17.5+/-4.1 ng/ml versus 13.9+/-4.1 ng/ml; P<0.05), total area under the plasma concentration-time curve (194.8+/-88.9 ng h/ml versus 105.9+/-33.0 ng h/ml; P<0.001), and elimination half-life (11.1+/-4.6 h versus 6.8+/-2.8 h; P<0.01) of etizolam. No significant change was induced by carbamazepine in the two pharmacodynamic parameters.The present study suggests that carbamazepine induces the metabolism of etizolam.