OBJECTIVE: Routine clinical pharmacokinetic data collected from epileptic out-patients who received phenytoin (PHT) were analysed to estimate population pharmacokinetic parameters (PPK) using NONMEM program. METHODS : There were 361 steady-state serum PHT concentrations and associated dosage(mg· d-1) from 219 outpatients. RESULTS: The Vin and Km of PHT in a 60kg adult out-patients without combination with other drugs (phenobarbital, clonazepam or diazepam) were estimated to be 43 3 mg·d-1 and 5.84mg·mg-1 r...