Effect of Carbamazepine 10, 11-Epoxide on Serum Carbamazepine Measurement Using a New CMIA Assay: Comparison of Values Obtained by Using PETINIA, CEDIA and Liquid Chromatography Combined with Tandem Mass Spectrometry

摘要

Background. Carbamazepine is a classical anticonvulsant that requires therapeutic drug monitoring. We evaluated the effect of carbamazepine 10, 11 epoxide on a new chemiluminescent immunoassay (CMIA) for application on the Architect i1000SR analyzer. Materials and Methods. Carbamazepine concentrations were measured in 40 specimens collected from patients taking carbamazepine using a PETINIA assay (Vista 1500 analyzer), a CEDIA assay (Cobas c501 analyzer) and the new CMIA assay (Architect i1000 analyzer). In addition, carbamazepine and carbamazepine 10, 11-epoxide concentrations were determined using a reference liquid chromatography combined with a tandem mass spectrometry (LC/MS/MS) reference method in another 15 specimens. These specimens were further analyzed using the PETINIA, CEDIA and CMIA assays. Results and Discussion. A good correlation (regression equation: y = 0.9605x+0.2788, n=40, r=0.98) between values obtained by using the CEDIA assay (x-axis) and the CMIA assay (y-axis) was observed but the PETINIA assay showed significant bias compared to the CMIA assay (regression equation: y=0.8191x+0.3069, n=40, r=0.97). The bias was due to high cross-reactivity of epoxide with the PETINIA assay as revealed by comparing carbamazepine values obtained by LC-MS/MS with these three assays. Conclusion. The new CMIA assay is suitable for therapeutic drug monitoring of carbamazepine because values correlated well with the CEDIA assay values (n=40) as well as LC-MS/MS reference method values in 15 specimens.