Development and validation of SPE-HPLC method for the determination of carbamazepine and its metabolites carbamazepine epoxide and carbamazepine trans-diol in plasma

SPE-HPLC method has been developed and validated for rapid analysis of carbamazepine and its two metabolites carbamazepine epoxide and carbamazepine trans-diol in human plasma. The analysis was performed using C18 Bakerbond-BDC analytical column (250 mm x 4.6 mm i.d., particle size 5 ?m). The optimal conditions for the separation were established with the mobile phase acetonitrile - 10 mM phosphate buffer, pH 7.0 (30:70, v/v) at the flow rate of 1.5 mL min-1, temperature 35?C, and UV detection at 210 nm. Total run time was about 8 minutes. SPE procedure for extraction of the analytes from plasma sample was developed using Oasis HLB cartridges and subsequently eluate was injected into the HPLC system for analysis. Afterwards, SPE-HPLC method was subjected to validation. Linearity was obtained over the concentration range of 0.2-25 ?g/mL for carbamazepine, carbamazepine epoxide and carbamazepine trans-diol with correlation coefficients higher than 0.995. The method showed good intra-day and inter-day precision with relative standard deviation below 7.96%, while accuracy ranged from 92.09% to 108.5% for all analytes. Finally, the method was successfully applied to analysis of plasma samples of epileptic patients in monotherapy and polytherapy. [Acknowledgments. Projekat Ministarstva nauke Republike Srbije, br. OI 172033].