Abstract: AIM: To develop a simple and sensitive method for the simultaneous determination of carbamazepine (CBZ), lamotrigine (LTG), phenobarbital (PB), phenytoin (PHT) and 10, 11-carbamazepine epoxide (CBZE)in human plasma by reversed-phase high performance liquid chromatography (RP-HPLC).METHODS: 0.1 ml serum was extracted from dichloromethane:isopropanol (95 ∶5).Flurazepam(FZP)was adopted as internal standard.The mobile phase was composed of acetonitrile-potassium phosphate buffer (30 ∶70).The ultraviolet detector was set at 220 nm and the analysis through Symmetry RP18 stainless steel column was taken at 37 ℃.RESULTS: Peak area ratios of every drug vs.internal standard were fit to a least squares linear regression algorithm with a 1 (concentration)2 weighting in the concentration range of each drug (CBZ:0.47-30.00 mg·L^-1, LTG:0.63-40.00 mg·L^-1, PB:1.25-80.00 mg·L^-1, PHT:0.63-40.00 mg·L^-1, CBZE:0.31-20.00 mg·L^-1).The recoveries were more than 95% (95%-104%, n =6).The relative standard deviations of within-day and between-day were less than 4% (0.76%-3.97%, 1.34%-3.76%, n =6).CONCLUSION: The method is sensitive, accurate, rapid and simple.It is suitable for the clinical monitoring on most antiepileptic drugs and can provide veridical and credible data for the study of population pharmacokinetics and for the implement of individual regimen.

Key words: antiepileptic drugs, metabolite, RPHPLC, serum concentrations, therapeutic drug monitoring