Population Analysis of the Dose-Dependent Pharmacokinetics of Zonisamide in Epileptic Patients

概要

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The pharmacokinetics of zonisamide was studied using routine therapeutic drug monitoring data from 68 epileptic patients. The 266 serum concentration data at steady-state after repetitive oral administration were analyzed using the nonlinear mixed effects model (NONMEM) program designed for estimation of population pharmacokinetic parameters. A one-compartment model with dose-dependent clearance was used for the pharmacokinetic analysis of zonisamide. The volume of distribution (V) was estimated to be 1.27 l/kg in a typical 33-kg patient, assuming that the bioavailability of orally administered zonisamide is 100%. The maximal daily dose to be cleared (V_<max>) and the concentration giving half maximal clearance (a Michaelis-Menten constant) was 27.6 mg/d/kg and 45.9 μg/ml, respectively. The parameter of a power function of weight to adjust V and V_<max> was estimated to be 0.741. In addition, V_<max> for zonisamide appears to be 13% increased in patients receiving carbamazepine concurrently. The population pharmacokinetic parameters of zonisamide will be useful for designing dosage regimens in epileptic patients.
社団法人日本薬学会の論文
1994-02-15