A Novel Enantioselective Microassay for the High-Performance Liquid Chromatography Determination of Oxcarbazepine and Its Active Metabolite Monohydroxycarbazepine in Human Plasma

Abstract

A simple and innovative assay is described that allows the determination of the antiepileptic drug oxcarbazepine and the chiral separation of the two enantiomers of its active metabolite monohydroxycarbazepine (licarbazepine). The assay requires liquid-liquid extraction of the sample (200 microL) into tert-butyl methyl ether and dichloromethane, drying of the organic phase under a nitrogen stream, reconstitution with the mobile phase, and injection in the high-performance liquid chromatography system after filtering. Separation of oxcarbazepine, R-(-)-monohydroxycarbazepine, S-(+)-monohydroxycarbazepine, and the second-step metabolite 10,11-trans-dihydroxycarbamazepine (racemate) is achieved with a Chiralcel ODR column and potassium hexafluorophosphate/acetonitrile as mobile phase. Detection is by ultraviolet absorbance at 210 nm. Standard curves are linear (r2 > or = 0.999) over the range of 0.1 to 25 microg/mL for each analyte with a limit of quantification of 0.1 microg/mL (1 ng injected) for all compounds. Within-day and between-day precision is better than 12% and within-day and between-day accuracy is between 99% and 116% for each compound. These performance characteristics are adequate for pharmacokinetic studies and for therapeutic drug monitoring. However, because the two enantiomers of monohydroxycarbazepine exhibit similar pharmacologic activity, nonenantioselective assays are likely to be more cost-effective for therapeutic drug monitoring purposes.

Antipsychotic and Antiepileptic Drugs in Bipolar Disorder: The Importance of Therapeutic Drug Monitoring

“…Several papers deal with the determination of OXCBZ and its metabolites or other CNS drugs in human plasma [270][271][272][273][274][275][276][277][278][279][280][281][282][283], saliva [284][285][286] and urine [287,288] from epileptic patients. Currently, HPLC with UV detector is much more widespread [271-276, 278, 280, 281, 283-288]; other papers used HPLC coupled with mass spectrometry [270] or diode array detection (DAD) [279,282].…”

Development and validation of an enantioselective liquid-chromatography/tandem mass spectrometry method for the separation and quantification of eslicarbazepine acetate, eslicarbazepine, R-licarbazepine and oxcarbazepine in human plasma

“…In recent years several methods to measure ESL and its metabolites in human plasma have been reported [5][6][7][8]; however, the published methods were not sufficiently sensitive for quantification of OXC and R-Lic, with a lower limit of quantification ranging [7,9]. Existing HPLC with UV detector methods hardly reach the limit of quantification required for reliable measurements of minor metabolites at the levels found in circulation.…”

Health benefits of isoflavones in functional foods? Proteomic and metabonomic advances

“…Metabonomics has been successfully applied to toxicology, pharmaceutical drug discovery and identification of biomarkers in disease development and diagnosis (Filler, 2007;Keun, 2006;Mazzucchelli et al, 2007;Nicholson et al, 2002;Plumb et al, 2002;Plumb et al, 2003;Zhang et al, 2000). Metabonomics can also be used to investigate the effect of dietary components on metabolic regulation in biological systems by analysing the global metabolite profile.…”