|
Phenytoin as an anticonvulsant agent is widely used in the treatment of epilepsy, especially in tonic-clonic seizure. Phenytion is predominantly metabolized by the liver and follows non-linear pharmacokinetics(dose-dependent). Plasma concentration of phenytoin is variable depending on age, body weight, renal failure, liver failure, concurrent drugs, bioavailability, compliance and race, furthermore phenytoin has narrow therapeutic window, so clinical pharmacokinetic evaluation is essential for individualized dosage adjustment. This fact spurred research aimed at applying to out-patients the pharmacokinetic dosing methods commonly used for therapeutic monitoring of phenytoin In our study, 41-adults out-patient group in the mean age of 29 years were selected. These patients who had normal renal and liver function treated with phenytion 300 ㎎ per day chronically. The phenytoin blood concentrations of the patients assumed as steady-state concentration were taken and measured by fluorescence polarization immunoassay. We classified the 41 patients into three categories based on the blood concentrations following as optimal therapeutic range(10-20 ㎍/㎖), subtherapeutic range(less than 10 ㎍/㎖) and toxic range(more than 20 ㎍/㎖). On the other hand, we analyzed the dose (300㎎) into the dose rate(㎎/㎏/day) based on the actual body weights of individuals and then classified the patients into the three therapeutic range groups, too. According to our study, it is more desirable to administer the phenytoin depend on dose rate based on the body weight(4-6 ㎎/㎏/day) rather than routine dose (300 ㎎/㎏/day). It also needs to adjust dosage after the clinical pharmacokinetic evaluation because the percentage of the optimal therapeutic range in patients administered by 4-6㎎/㎏/day dose, was only 29.3％.
|