Analysis of free concentrations of lamotrigine and active oxcarbazepine metabolite in clinical patients by hollow-fiber centrifugal ultrafiltration.

To establish a simple and accurate method to explore the correlation between free and total concentrations of lamotrigine (LTG) and the active oxcarbazepine metabolite monohydroxy derivative (MHD) (10,11-dihydro-10-hydroxycarbamazepine) in clinical patients. Serum samples were prepared by hollow-fiber centrifugal ultrafiltration and then injected into UPLC for analysis. Absolute recovery was as high as approximately 90.1-98.6% with excellent precision (relative standard deviation <6.7%). Analysis time was reduced to 5 min. There were significant individual differences in the protein binding rates of both LTG and MHD that were probably due to the use of different clinical patients. Free concentrations of LTG and MHD cannot be estimated by total concentration in specific clinical patients. Free drug monitoring of LTG and MHD in clinical therapeutic drug monitoring is important and essential.