Relationship between mono-hydroxy-carbazepine serum concentrations and adverse effects in patients on oxcarbazepine monotherapy

Development and Validation of a Highly Sensitive and Rapid LC-MS3 Strategy to Determine Oxcarbazepine and Its Active Metabolite in the Serum of Patients with Epilepsy and Its Application in Therapeutic Drug Monitoring

A sensitive and rapid bioanalytical method based on the LC-triple-stage fragmentation (LC-MS³) strategy on a hybrid triple quadrupole-linear ion trap mass spectrometer in combination with protein precipitation extraction for sample pretreatment has been developed and validated for the simultaneous determination of the antiepileptic drug oxcarbazepine (OXC) and its main active metabolite (MHD) in human serum. The separation was performed on a Waters XBridge BEH C18 column (2.5 µm, 2.1 × 50 mm) in isocratic elution with 0.1% formic acid in water and methanol (50:50, v:v) as the mobile phase. The run time for each sample was 2.0 min. The calibration curves ranging from 25 to 1600 ng/mL for OXC and from 0.5 to 32 μg/mL for MHD showed correlation coefficients (r) better than 0.99. All of the validation data, such as precision, accuracy and other parameters, fit the requirements of the current bioanalytical method validation guidelines. The LC-MS³ method for quantitation of OXC and MHD was compared with the LC-MRM based method. Passing–Bablok regression coefficients and Bland–Altman plots showed that the developed LC–MS³ method is a reliable method for quantitative analysis of OXC and MHD. The proposed LC-MS³ method was successfully applied to determine the serum concentrations of OXC and MHD to support a clinical study.

Analysis of influencing factors on monohydroxylated derivative of oxcarbazepine plasma concentration in children with epilepsy

PURPOSE

This study aimed to investigate the factors affecting the plasma concentration of monohydroxylated derivative (MHD) of oxcarbazepine (OXC) in children with epilepsy.

METHODS

We recruited 125 children with epilepsy who received OXC monotherapy. Among them, 16 single nucleotide polymorphisms were detected by MassARRAY genotyping technology to evaluate the influence of related factors on the plasma concentration of OXC monotherapy. MHD is the main active metabolite of OXC, and its plasma concentration was measured by high-performance liquid chromatography (HPLC).

RESULTS

Bivariate correlation analysis revealed that concentration-dose ratio (CDR) increased with weight, and the corresponding maintenance dose decreased with weight (r=0.317, P=0.001 for CDR; r=-0.285, P=0.000 for OXC maintenance dose). The duration of seizure was found to be associated with CDR (0.90 ± 0.36 vs 0.74 ± 0.26 μg·kg/mg/mL for ≥6 years vs <1 year, P=0.028; 0.90 ± 0.36 vs 0.64 ± 0.21 μg·kg/mg/mL for ≥6 years vs 1-3 years, P=0.004; 0.90 ± 0.36 vs 0.69 ± 0.18 μg·kg/mg/mL for ≥6 years vs 3-6 years, P=0.031). The CDR of patients with ABCB1 rs1045642 mutation homozygous GG type is higher than heterozygous AG type (0.79 ± 0.30 vs 0.68 ± 0.20 μg·kg/mg/mL for AG vs GG, P=0.032).

CONCLUSION

This study clarified the association of weight, duration of seizure, and gene polymorphisms of ABCB1 rs1045642 with MHD plasma concentration in children with epilepsy.

LC-MS/MS quantification of levetiracetam, lamotrigine and 10-hydroxycarbazepine in TDM of epileptic patients

BACKGROUND

To minimize drug-related toxicity and monitor dosing regimens, an ultra-sensitive, simple and high-throughput analytical method for therapeutic drug monitoring (TDM) is required.

METHODS

A novel LC-MS/MS bioassay of levetiracetam (LEV), lamotrigi1/ne (LTG) and 10-hydroxycarbazepine (MHD) in human plasma was established. The analytes were separated on a Hypersil GOLD^TM C18 column under a 2.5-min isocratic elution after one-step protein precipitation. MS detection was performed under ESI+ mode fitted with selected reaction monitoring.

RESULTS

The validated ranges were 0.1-20 μg/mL for LTG, 0.3-60 μg/mL for MHD and LEV. The intra- and inter-batches of precision and accuracy was within ±15%. The novel method met all other criteria.

CONCLUSION

This method can be used to monitor drug concentrations and decision-making in epileptic patients.

Population pharmacokinetic model development and its relationship with adverse events of oxcarbazepine in adult patients with epilepsy

This study aimed to develop a pharmacokinetic (PK) model of oxcarbazepine (OXC) and analyse the relationship between monohydroxylated derivative (MHD), an active metabolite of OXC, and the adverse events of OXC. We obtained 711 OXC samples from 618 patients with epilepsy who were enrolled in the Epilepsy Registry Cohort of Seoul National University Hospital from February 2011 to January 2014. The plasma PK model was developed using a nonlinear mixed-effect modelling method with NONMEM (ver 7.3). A one-compartment model with a first-order absorption model and proportional residual error adequately described the MHD concentration–time profiles. The only covariate incorporated for CL/F and V/F was body weight. Of the 447 patients analysed, 28 (6.26%) had dose-related adverse events (DRAEs), which were dizziness, somnolence, headache, and diplopia. For DRAE occurrence, the cut-off values of the MHD trough and AUC were 12.27 mg/L (specificity 0.570, sensitivity 0.643) and 698.5 mg h/L (specificity, sensitivity 0.571), respectively. Multivariate analysis showed the sole dizziness symptom was significantly associated with both the MHD trough and the AUC (p = 0.013, p = 0.038, respectively). We newly developed a population PK model using sparse sampling data from patients with epilepsy, and the model better reflects the actual clinical situation.

Comparison of oxcarbazepine efficacy and MHD concentrations relative to age and BMI: Associations among ABCB1, ABCC2, UGT2B7, and SCN2A polymorphisms

Genetic polymorphisms are related to the concentration and efficacy of oxcarbazepine (OXC). 10-Hydroxycarbazepine (MHD) is the major pharmacologically active metabolite of OXC, and it exerts an antiepileptic effect. This study aimed to explore the connection between the MHD concentration and genes such as ATP-binding cassette B1 (ABCB1), ATP-binding cassette C2 (ABCC2), UDP-glucuronosyltransferase-2B7 and sodium voltage-gated channel alpha subunit 2 (SCN2A), which participate in the antiepileptic function of OXC.Total 218 Chinese epileptic patients, were stratified into different groups according to their age, body mass index (BMI) and OXC efficacy. The genotypes of 7 single nucleotide polymorphisms in all subjects were determined by polymerase chain reaction-improved multiple ligase detection reaction assay. The MHD plasma concentration was detected by high-performance liquid chromatography and then standardized through dosage and body weight.In general, the ABCC2 rs2273697 mutant (P = .026) required a significantly higher standardized MHD concentration. For age groups, carriers of the ABCC2 rs2273697 mutant showed a significantly higher standardized MHD concentration than noncarriers in the juvenile group (P = .033). In terms of BMI, a significantly higher standardized MHD concentration was found in the ABCB1 rs2032582 mutant of the normal weight group (P = .026). The SCN2A rs17183814 mutant required a significantly higher OXC maintenance (P = .014) in the low-weight group, while lower OXC maintenance dose (P = .044) and higher standardized MHD concentration (P = .007) in the overweight group.The ABCC2 rs2273697 polymorphism was significantly associated with MHD plasma concentration in the whole patient cohort and in patients stratified by different ages, this finding provides potential theoretical guidance for the rational and safe clinical use of OXC.

Extended-release drug formulations for the treatment of epilepsy

INTRODUCTION

Extended-release (ER) preparations are either available or have been tested for several antiepileptic drugs (AEDs). Indeed, they may be helpful in improving efficacy, tolerability, adherence, compared to the corresponding immediate release (IR) preparations available. The use of ER preparations has been advocated in women of childbearing age and is - depending on the drug - especially helpful in patients who are treated in combination with enzyme inducing AEDs as well as in children.

AREAS COVERED

Clinical and pharmacokinetic studies on ER formulations of AEDs were identified by a PubMed literature research. Further references were added from the authors' personal knowledge and from the reference lists of the identified studies. Reviews and expert commentaries were included, where necessary.

EXPERT OPINION

Unfortunately, studies providing direct comparisons of ER and IR formulations of a given drug are only available for a handful of drugs. ER preparations are especially helpful in drugs with a short elimination half-life and concentration-depending efficacy and tolerability.