Simultaneous quantification of oxcarbazepine and its active metabolite in spiked human plasma using ultra performance liquid chromatography-MS/MS.

Aim: Clinical monitoring of oxcarbazepine (OXC) and its metabolite licarbazepine (MHD) in biological matrix requires a sensitive and validated analytical method. The aim of this study is to develop and validate an optimized ultra performance liquid chromatography-MS/MS based bioanalytical method for the simultaneous estimation of OXC and its metabolite MHD in human plasma, using deuterated internal standard method. Materials & methods: A reverse phase ultra performance liquid chromatography analysis and mass spectrometric detection was performed using electrospray ionization in positive ion mode as interface, multiple reaction monitoring as mode of acquisition. Results & conclusion: The linearity range was 10-4011 ng/ml for OXC and 40-16061 ng/ml for MHD. The kinetic parameters were calculated and compared for bioequivalence. This method fulfilled the validation guidelines, could be employed for determining bioavailability and in new formulation development studies.

Development and validation of an innovative UPLC method to quantify lacosamide, oxcarbazepine, and lamotrigine in the serum of children with epilepsy in China.

This study has developed and validated a novel UPLC method to quantify lacosamide (LCM), oxcarbazepine (OXC), and lamotrigine (LTG) in children with epilepsy in Xinjiang, China. Phenytoin sodium was used as the internal standard. The mobile phase contained ammonium dihydrogen phosphate solution (10 mmol/L, pH = 4.0) and methanol (55:45, v/v). The flow rate, injection volume, column temperature, and detection wavelength were 0.2 mL/min, 2 µL, 30°C, and 240 nm, respectively. The method was linear within 0.5-40, 2.5-80, and 2.5-40 µg/mL for LCM, 10-hydroxycarbazepine (MHD), and LTG, respectively (r2 ≥ 0.998). The intra- and inter-day precision as measured by the relative standard deviation values was between 1.36 and 4.50, 0.54 and 1.91, and 0.58 and 1.56%. Recovery ranged from 96.58 to 106.22%. All serum samples could be maintained for up to 3 h at ambient temperature, 24 h at 4°C, 30 days at -30°C, and after successive freeze-thaw cycles (24 h per cycle) in the absence of significant degradation.

Accurate and simple determination of oxcarbazepine in human plasma and urine samples using switchable-hydrophilicity solvent in GC-MS.

This work presents a sensitive and rapid analytical method for the determination of oxcarbazepine in human plasma and urine samples. A vortex-assisted switchable hydrophilicity solvent-based liquid phase microextraction (VA-SHS-LPME) was used to preconcentrate oxcarbazepine from the samples before the determination by gas chromatography mass spectrometry. The switchable hydrophilicity solvent was synthesized by protonating N,N-dimethylbenzylamine with carbon dioxide to make it totally miscible with an equivalent volume of water. Parameters of the VA-SHS-LPME method including volume of switchable hydrophilicity solvent, concentration/volume of sodium hydroxide and vortex period were systematically optimized. Under the optimum conditions, good linearity ranging from 27.03 to 353.47 µg/kg was obtained for the analyte. Limit of detection and quantitation values were found to be 6.2 and 21 µg/kg (mass base), respectively. The relative standard deviation was calculated as 6.9% for six replicate measurements of the lowest concentration of the calibration plot. Satisfactory recovery results were calculated in the range of 97-100% for human plasma and urine samples spiked at five different concentrations.

Development of an online solid-phase extraction-liquid chromatography-mass spectrometric analysis of oxcarbazepine and its active metabolite licarbazepine from plasma with a direct injection step.

We developed an online solid phase extraction procedure using a hydrophilic-lipophilic balance sorbent, with reversed-phase liquid chromatography-high-resolution mass spectroscopy for the determination of oxcarbazepine and its active metabolite licarbazepine in plasma samples. The analytes were detected using a high-resolution Q Orbitrap mass spectrometer with targeted-selected ion monitoring (t-SIM) in positive scan mode. Under the optimized conditions, the method was linear with R2 values >0.99. The method was linear from 0.008 to 2.000 µg mL-1 and the lower limit of quantification was 0.008 µg mL-1 for both oxcarbazepine and licarbazepine. Recoveries ranged from 92.34 to 104.27% and from matrix-matched samples from 94.26 to 104.19%. The intraday and interday precision RSD values were <9.13% with an associated accuracy of 92.71 to 104.06%. The total time for the one step online procedure was only 8 min. This method provides a direct and accurate measurement for therapeutic drug monitoring of oxcarbazepine and its active metabolite licarbazepine.

Quantitation of Oxcarbazepine Clinically in Plasma Using Surfaced-Enhanced Raman Spectroscopy (SERS) Coupled with Chemometrics.

Nondestructive, sensitive, near-real-time quantitative analysis approaches are gaining popularity and attention, especially in clinical diagnosis and detection. There is a need to propose an alternative scheme using surface-enhanced Raman spectroscopy (SERS) assisted by chemometrics to improve some defects existing using other analytical instruments to meet clinical demands. In this study, clinical drug oxcarbazepine (OXC) in human blood plasma has been quantified and detected using this method. Partial least squares regression (PLSR) modeling was employed to assess the relationship between full SERS spectral data and OXC concentration. The calibration set's correlation coefficient of the model is > 0.9, the result suggests that this method is favorable and feasible. Furthermore, other multivariate calibration algorithms like Monte Carlo cross-validation (MCCV) sample set partitioning based on joint XY distances (SPXY), adaptive iteratively reweighted penalized least squares (AIR-PLS), moving window partial least squares regression (MWPLS), and leave-one-out cross-validation were used to handle these spectral data to obtain an accurate predictive model. The results achieved in this study provide a possibility and availability for us to apply SERS in combination with chemometrics to diagnosis detection.

Population pharmacokinetics of oxcarbazepine active metabolite in Chinese paediatric epilepsy patients and its application in individualised dosage regimens.

PURPOSE: Oxcarbazepine (OXC) is an antiepileptic drug metabolised to active 10-monohydroxy derivative (MHD) following oral administration. There are no MHD population pharmacokinetic (PPK) models that describe the influence of genetic factors on MHD pharmacokinetics (PK). We developed a PPK model of MHD to investigate gene polymorphism of enzymes associated with MHD PK in Chinese paediatric epilepsy patients and evaluated its utility for dose individualisation. METHODS: Data were prospectively collected from 141 paediatric epilepsy patients (aged ≤ 14 years) who received OXC therapy at the First Affiliated Hospital of Fujian Medical University. The trough concentrations at steady state were determined by enzyme-multiplied immunoassay. Patients were genotyped for four single nucleotide polymorphisms (UGT2B7 802T>C, UGT1A9 I399C>T, ABCB1 3435C>T, and ABCB2 1249G>A). Patient gender, age, body weight (BW), hepatorenal function, and co-administrations were recorded. The PPK model was developed using nonlinear mixed-effects modelling software. The clinical performance of the final model was evaluated by including additional paediatric patients (n = 20) in the validation group. RESULTS: Oral clearance of MHD was significantly influenced by BW. The MHD PK was unrelated to the other covariates, such as the four single nucleotide polymorphisms and co-administration with new-generation antiepileptic drugs. The final BW-dependent exponent model showed the best fit with our data and predicted the trough concentrations in the validation group more accurately than the basic model. A new dosing strategy combining the dosage guideline and Bayesian method is proposed to individualise OXC regimens. CONCLUSION: A PPK model was established to estimate individual MHD clearance in paediatric patients taking OXC to develop individualised OXC dosing regimens for Chinese paediatric epilepsy patients.

Development and Validation of an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method for the Concurrent Measurement of Gabapentin, Lamotrigine, Levetiracetam, Monohydroxy Derivative of Oxcarbazepine, and Zonisamide Concentrations in Serum in a Clinical Setting.

BACKGROUND: Therapeutic drug monitoring of antiepileptic drugs (AEDs) is often necessary to prevent associated destructive toxicities. Tandem mass spectrometry (MS/MS) with stable-isotope-labeled internal standards is considered the gold standard for the measurement of AEDs. This study presents the development and validation of a clinical ultra-performance liquid chromatography-MS/MS method for the concurrent measurement of gabapentin, lamotrigine, levetiracetam, monohydroxy derivative of oxcarbazepine, and zonisamide in human serum. METHODS: To determine the optimal assay analyte range, one year of AED therapeutic drug monitoring results (n = 1825) were evaluated. Simple protein precipitation with acetonitrile containing isotopically labeled internal standards was used. Reverse-phase ultra-performance liquid chromatography chromatographic separation was used, having a total run time of 3 minutes. Quantification of analytes was accomplished using electrospray ionization in positive ion mode and collision-induced dissociation MS. Assay parameters were evaluated per Food and Drug Administration bioanalytical guidelines. RESULTS: After evaluating internal patient data, the analytical measuring range (AMR) of the assay was established as 0.1-100 mcg/mL. All AEDs were linear across the AMR, with R values ranging from 0.9988 to 0.9999. Imprecision (% coefficient of variation) and inaccuracy (% difference) were calculated to be <20% for the lower limit of quantitation and <15% for the low, mid, and high levels of quality controls across the AMR. All AEDs demonstrated acceptable assay parameters for carryover, stability under relevant storage conditions, matrix effects, recovery, and extraction and processing efficiency. In addition, the assay displayed acceptable concordance to results obtained from a national reference laboratory, with Deming regression R of 0.99 and slope values ranging from 0.89 to 1.17. CONCLUSIONS: A simple, cost-effective, and robust ultra-performance liquid chromatography-tandem mass spectrometry method for monitoring multiple AEDs was developed and validated to address the clinical needs of patients at our institution.