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.
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.


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.


CONCLUSIONS
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.


CONCLUSIONS
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.
Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Salt Lake City, UT, USA Amitava.Dasgupta@uth.tmc.edu.
Amitava
A
Dasgupta
Laboratory Services, Memorial-Hermann Hospital at Texas Medical Center, Salt Lake City, UT, USA.
Bonnette
B
Davis
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT, and Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT, USA.
Matthew H
MH
Slawson
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT, and Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT, USA.
Kamisha L
KL
Johnson-Davis
D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000097:blood; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008163:Luminescent Measurements / Q000379:methods*; D012044:Regression Analysis; D053719:Tandem Mass Spectrometry / Q000379:methods*
D002220:Carbamazepine; C012227:carbamazepine epoxide
CEDIA; CMIA; Carbamazepine; LC-MS/MS; PETINIA