Validation of the analysis of carbamazepine and its 10,11-epoxide metabolite by high-performance liquid chromatography from plasma: comparison with gas chromatography and the enzyme-multiplied immunoassay technique.

An improved procedure for the determination of carbamazepine (CBZ) and its main active metabolite carbamazepine-10,11-epoxide (CBZ-e) in serum is described. The validation of this procedure shows that the limits of detection are lower than 80 ng/ml for CBZ and 7 ng/ml for CBZ-e. The relative standard deviation does not exceed 4.7% for both compounds in an inter-day precision test. In the intra-day precision test the relative standard deviations are 1.9% for CBZ-e and 1.1% for CBZ. A comparison of the described procedure with gas chromatography and the enzyme-multiplied immunoassay technique shows good agreement, but gas chromatography seems to have a relative poor reliability.