Development and validation of an HPLC method for determination of carbamazepine in human plasma and applications to a therapeutic drug monitoring study

Background and Aims: Carbamazepine (CBZ) is an antiepileptic drug, which is prescribed as a first-line drug for the treatment of partial and generalized tonic--clonic epileptic seizures. The aim of this study was to develop and validate a simple, fast and reliable HPLC method for the determination of carbamazepine in human plasma. Methods: Chlorpromazine (CPR) was used as an internal standard. The separation was conducted with a C18 reverse-phase column (150x3.9 mm, 5 [micro]m) at 30[degrees]C, using a mobile phase prepared with 20 mM KH2PO4, acetonitrile and methanol (6:3:1, v/v/v) by isocratic elution. Results: The method was linear between 0.5 and 40 [micro]g/mL, determined by 10 individual calibration points. Total run time was [less than or equal to] 5 mins. Accuracy (RE%) values were determined between (-5.6) and 3.6%, and precision was determined at [less than or equal to]4.2%. Limit of detection (LOD) was 0.04 [micro]g/mL. The robustness test results of the method showed good values. Plasma CBZ of (n=30) those receiving CBZ quantities ranging from 0.2 to 1.2 g/day were measured with this method, and following analyses of their concentrations were found to be between 0.1 and 11.4 [micro]g/mL (6.2[+ or -]2.4 [micro]g/mL). While all plasma sample analyses were applied properly, it was observed that 16 (53.3%) of the plasma samples had CBZ lower than the recommended range. In addition to that, female patient plasma-CBZ levels were found significantly higher than male plasma contents (p