Antiepileptic drug therapeutic regimens often need to be adjusted individually on the basis of serum assays. We aimed to develop a quantitative, fast, and sensitive liquid chromatography–tandem mass spectrometry method to simultaneously analyze carbamazepine, oxcarbazepine, and the 10-11 epoxide carbamazepine and 10-hydroxy carbazepine (mono-hydroxy derivative, 10,11-Dihydro-10-hydroxycarbamazepine) metabolites, in human serum.
Serum samples were deproteinized by acetonitrile spiked with dansyl-norvaline as internal standard. Compounds were separated on a reversed-phase high-performance liquid chromatography over a total run time of 10 minutes. Serum concentrations were then measured by means of a triple quadrupole tandem mass spectrometer, set up in positive mode and multiple reaction monitoring.
Calibration curves (0.08–50 mcg/mL for carbamazepine and 10,11-dihydro-10-hydroxycarbamazepine; 0.03–20 mcg/mL for oxcarbazepine and epoxide carbamazepine) were linear, with a mean correlation coefficient >0.999. Both the intra- and interassay imprecision and inaccuracy were within 10%. The absolute recovery ranged from 98% to 103% for all analytes.
The method requires minimal sample preparation. Volume of the sample is lower and run time shorter than required by previous published liquid chromatography–tandem mass spectrometry methods. Results are accurate. The method seems, therefore, to be reliable and economically suitable for routine analysis of antiepileptic drugs monitoring in clinical settings.