Studies on The Plasma Analysis and Bioavailability of Phenytoin in Human

A developed assay method to evaluate the pharmacokinetics of phenytoin in human plasma was investigated by reverse-phase HPLC-UV. We found the analytic condition that separate phenytoin from internal standard (triamcinolone acetonide) in human plasma sample at the wavelength of 225 nm. Proteins of the plasma samples were removed enough by using 0.1 N HC1. Mobile phase is consisted of buffer (pH3.0):CH3CN (65:35), and retention time of phenytoin is 8.2 min at a flow rate of 0.9 ml/min.. Tlie fundamental parameters such as linearity, accuracy, precision for this bioanalytical method validation were suitable to pharmacokinetic study and bioequvalence test. Eight volunteers in lasting were administered single dose of 100 mg of phenytoin (one tablet) orally together with 240 ml water for pharmacokinetic studies. The maximum concentration (0.82 ㎍/ml) of phenytoin was attained at 6.63 hour after dosing. T1/2 and AUC were 14.88 hr and 25.181 ㎍hr/ml respectively. According to our study, the accurate analysis for phenytoin achieved and the proposed guidance can be applied to pharmacokinetic study and bioequivalence test in human.