Analysis of Oxcarbazepine and the 10‐Hydroxycarbazepine Enantiomers in Plasma by LC‐MS/MS: Application in a Pharmacokinetic Study

Abstract

Oxcarbazepine is a second-generation antiepileptic drug indicated as monotherapy or adjunctive therapy in the treatment of partial seizures or generalized tonic-clonic seizures in adults and children. It undergoes rapid presystemic reduction with formation of the active metabolite 10-hydroxycarbazepine (MHD), which has a chiral center at position 10, with the enantiomers (S)-(+)- and R-(-)-MHD showing similar antiepileptic effects. This study presents the development and validation of a method of sequential analysis of oxcarbazepine and MHD enantiomers in plasma using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Aliquots of 100 μL of plasma were extracted with a mixture of methyl tert-butyl ether: dichloromethane (2:1). The separation of oxcarbazepine and the MHD enantiomers was obtained on a chiral phase Chiralcel OD-H column, using a mixture of hexane:ethanol:isopropanol (80:15:5, v/v/v) as mobile phase at a flow rate of 1.3 mL/min with a split ratio of 1:5, and quantification was performed by LC-MS/MS. The limit of quantification was 12.5 ng oxcarbazepine and 31.25 ng of each MHD enantiomer/mL of plasma. The method was applied in the study of kinetic disposition of oxcarbazepine and the MHD enantiomers in the steady state after oral administration of 300 mg/12 h oxcarbazepine in a healthy volunteer. The maximum plasma concentration of oxcarbazepine was 1.2 µg/mL at 0.75 h. The kinetic disposition of MHD is enantioselective, with a higher proportion of the S-(+)-MHD enantiomer compared to R-(-)-MHD and an AUC(0-12) S-(+)/R-(-) ratio of 5.44.

Oxcarbazepine and its active metabolite, (S)‐licarbazepine, exacerbate seizures in a mouse model of genetic generalized epilepsy

“…OXC is metabolized through a reduction process to active monohydroxy derivatives (MHDs), specifically a pair of enantiomers: (S)‐licarbazepine and (R)‐licarbazepine. OXC metabolism to MHDs is stereo‐selective in humans, with a higher proportion metabolized to (S)‐licarbazepine (ratio of plasma concentration area under the curve = 5.4) . Eslicarbazepine acetate (ESL) is a third‐generation AED in the CBZ class that was recently approved in Europe and the United States as adjunctive therapy in adults with partial‐onset seizures with or without secondary generalization .…”

“…OXC metabolism to MHDs is stereo-selective in humans, with a higher proportion metabolized to (S)-licarbazepine (ratio of plasma concentration area under the curve = 5.4). 5 Eslicarbazepine acetate (ESL) is a third-generation AED in the CBZ class that was recently approved in Europe and the United States as adjunctive therapy in adults with partialonset seizures with or without secondary generalization. 6 In humans, ESL undergoes extensive first-pass hydrolysis to its major active metabolite (S)-licarbazepine (also known as eslicarbazepine), which represents about 95% of the active moiety.…”

Avaliação de técnicas miniaturizadas de preparação de amostras em estudos estereosseletivos de biotransformação e metabolismo in vitro

“…Nesse trabalho, os ensaios foram avaliados em 2 níveis de concentração (baixa e alta) em quintuplicata. Posteriormente o coeficiente de variação e o erro relativo dessas amostras foram determinados com o auxílio de uma curva analítica preparada recentemente e não submetida a tais condições DE JESUS ANTUNES et al, 2013;FRENCH et al, 2014…”