[Simultaneous determination of carbamazepine and its active metabolite in serum by high performance liquid...

A rapid, sensitive and simple to operate high performance liquid chromatographic method for the simultaneous determination of carbamazepine (CBZ) and its metabolite (10,11-epoxide carbamazepine, ECBZ) in serum has been developed. The sample was extracted with ethyl acetate. The extract was evaporated to dryness and taken up with the mobile phase. Separation of CBZ and ECBZ was achieved by reversed phase chromatography using a mobile phase consisting of methanol-water (1:1) at flow rate of 0.8 ml/min on a 5 microns YWG C-18 column. Eluent was monitored at 214 nm. The method has a good linearity. The recoveries of CBZ and ECBZ were found to be 99.7% +/- 2.45 and 97.3% +/- 4.20 respectively. Precision studies for both within day and day-to-day at different concentrations provided CV values of less than 6%. Some commonly used anticonvulsants can be determined in the same procedure without interference. This method well adapted to the therapeutic monitoring of CBZ treated patients, as well as for pharmacokinetic studies.