HPLC Simultaneous Determination of Carbamazepine, Carbamazepine -10, 11 -epoxide, Phenytoin in Human Serum

Objective: To establish a HPLC method for the simultaneous determination of phenytoin ( PHT) , car-bamazepine (CBZ) and its metabolite (carbamazepine - 10, 11 - epoxide, CBZE) in human serum. Method: Acetonitrile, containing internal standard chlorzoxazone, was added to serum samples to precipitate the serum proteins. After centrifugation, the acetonitrile supernatant was injected for analysis by HPLC. Separation was a-chieved on a YWG - C18 analytical column (4.6 mm ×200 mm, 10μm) with a mobile phase of 13: 25: 62 acetonitrile - methanol -water. Detection was at 214 nm using an ultraviolet detector. Results: The calibration curve was linear within the range of 0. 4 - 16 μg·mL-1 of CBZ, 0. 2- 8 μg· mL-1 of CBZE and 1 -40 μg · mL-1 of PHT. The limit concentration of detection in CBZ, CBZE and PHT were 0.2, 0. 1 , 0. 5μg · mL-1 respectively. The average recovery of three drugs is nearly 100% and the RSD for the inter - and intra - day were less than 6% . Endogenous matrix and commonly used drugs did not interfere with the analysis. Conclusion: The method was convenient, sensitive and accurate. It was suitable for therapeutic monitoring of CBZ and/or PHT.