Discordant carbamazepine values between two immunoassays: carbamazepine values determined by ADVIA Centaur correlate better with those determined by LC-MS/MS than PETINIA assay

An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS)-based candidate reference measurement procedure for the quantification of carbamazepine-10,11-epoxide in human serum and plasma

OBJECTIVES

A reference measurement procedure (RMP) using isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) was developed and validated with the aim of accurately measuring carbamazepine-10,11-epoxide concentrations in human serum and plasma.

METHODS

To establish traceability to SI units, the absolute content of the reference material was determined using quantitative nuclear magnetic resonance (qNMR) spectroscopy. As sample preparation a protein precipitation protocol followed by a high dilution step was established. Chromatographic separation from carbamazepine and potential metabolites was achieved using a C18 stationary phase. Selectivity, specificity, matrix effects, precision and accuracy, inter-laboratory equivalence, and uncertainty of measurement were evaluated based on guidelines from the Clinical and Laboratory Standards Institute, the International Conference on Harmonization, and the Guide to the Expression of Uncertainty in Measurement.

RESULTS

The RMP demonstrated very good selectivity and specificity, showing no evidence of a matrix effect. This enabled accurate quantification of carbamazepine-epoxide in the concentration range of 0.0400-12.0 μg/mL. The intermediate precision was found to be less than 2.1 %, and the repeatability coefficient of variation (CV) ranged from 1.2 to 1.8 % across all concentration levels. Regarding accuracy, the relative mean bias varied from 1.4 to 2.5 % for native serum levels and from 1.4 to 3.5 % for Li-heparin plasma levels. The measurement uncertainty for single measurements ranged from 1.6 to 2.1 %.

CONCLUSIONS

In this study, we introduce a new LC-MS/MS-based candidate RMP for accurately measuring carbamazepine-10,11-epoxide in human serum and plasma. This novel method offers a traceable and dependable platform, making it suitable for standardizing routine assays and assessing clinically relevant samples.

Simultaneous determination of 24 antiepileptic drugs and their active metabolites in human plasma by UHPLC-MS/MS

Antiepileptic drugs (AEDs) have narrow therapeutic ranges with large individual variability. Routine therapeutic drug monitoring of AEDs was useful for dose optimization, but the common immunoassays could not meet the detection requirements of AEDs, especially for new generation AEDs. The aim of this study was to validate an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for simultaneously quantification of 24 AEDs and their active metabolites in human plasma and comparison with a chemiluminescent immunoassay (Simens ADVIA Centaur). The method validation was performed according to FDA and EMEA guidelines. A one-step protein precipitation by acetonitrile followed a five-fold dilution was performed for sample pretreatment. A 5.2 min gradient separation by methanol and 10 mM ammonium acetate was used for separation at 0.6 mL/min under 45 °C. Both positive and negative electrospray ionization were used. Isotopic internal standard was used for all analytes. The inter-day (36 days) accuracy and precision of quality control samples were - 1.07-13.69% and < 6.70% for all analytes. The stability was acceptable for all analytes under routine storing conditions. A total of 436 valproic acid, 118 carbamazepine, and 65 phenobarbital samples were determined twice by each of the UHPLC-MS/MS and immunoassay. Evaluated by Bland-Altman plot, the mean overestimation of the immunoassay compared to UHPLC-MS/MS was 16.5% for valproic acid, 5.6% for carbamazepine, and 40.3% for phenobarbital.

Development of a useful single-reference HPLC method for therapeutic drug monitoring of phenytoin and carbamazepine in human plasma

A single reference high-performance liquid chromatographic (SR-HPLC) method was developed and validated for the therapeutic drug monitoring (TDM) of phenytoin (PHT) and carbamazepine (CBZ) in plasma from patients. The analytical parameters evaluated were linearity, limit of quantification (LOQ), selectivity, accuracy, and stability according to the US Food and Drug Administration (FDA) guideline. The developed method shows good linearity (r2 > 0.999; LOQ-50 µg/mL), and LOQ values were 1.56 µg/mL for PHT and 0.40 µg/mL for CBZ at 254 nm. For the development of SR-HPLC method, we evaluated to improve the detection wavelength, stirred retention time, and stability for SR, and selected 5-(p-methylphenyl)-5-phenylhydantoin for PHT (relative molar sensitivity, RMS = 0.848) and 10-methoxyiminostilbene for CBZ (RMS = 0.263). The established differential definite quantities of PHT and CBZ in plasma samples were similar using the RMS and absolute calibration methods based on RSD < 5.10%. A preliminary application was performed using chemiluminescent immunoassay and SR-HPLC method, in which the detectable values of the correlation coefficient and the slope of the intercept were PHT: 0.964 and 0.992647, and CBZ: 0.969 and 1.072089, respectively. Based on these results, we propose that the SR-HPLC method with RMS would be offered to the useful and accurate TDM of various medicines in plasma/serum samples.

LC–MS3 Strategy for Quantification of Carbamazepine in Human Plasma and Its Application in Therapeutic Drug Monitoring

This study developed a detection method based on the strategy of HPLC/MS³ and verified its suitability by quantifying carbamazepine in human plasma. The high-performance liquid chromatography–tandem mass spectrometry (HPLC/MS³) system was performed using a Shimadzu UFLC XR liquid chromatography and a SCIEX QTRAP^® 5500 linear ion trap triple quadrupole mass spectrometer. The specific operation was as follows: the sample protein was firstly precipitated using methanol, then carbamazepine and carbamazepine-D₂N¹⁵ were separated on an ACQUITY UPLC HSS T3 column using the gradient elution with solvent A (0.1% formic acid) and solvent B (0.1% formic acid in acetonitrile) at a flow rate of 0.25 mL/min. Each sample was run for 7 min. This method was validated for various parameters including accuracy, precision, selectivity, linearity, LLOQ, etc. Only 5 μL of sample plasma could obtain the result of LLOD 0.5 µg/mL. The intra-day and inter-day precision was <8.23%, and accuracy was between −1.74% and 2.92%. This method was successfully used for monitoring the blood concentration of epilepsy patients after carbamazepine treatment.

Determination of serum carbamazepine and its metabolite by validated tandem mass spectrometric method and the effect of carbamazepine on various hematological and biochemical parameters

OBJECTIVES

The study aimed to develop a validated LC-MS / MS method for the measurement of carbamazepine and carbamazepine-10,11-epoxide (CBZE) levels, to compare the carbamazepine concentrations measured by AbSciex API 3200 LC-MS/MS and Beckman Coulter Emit® 2000 immunoassay and to investigate the effect of carbamazepine concentrations on various hematological and biochemical parameters.

METHODS

For the measurement of carbamazepine and CBZE levels, a validated LC-MS / MS method was developed. Serum carbamazepine levels of patients were measured by AbSciex API 3200 LC-MS / MS and Beckman Coulter Emit® 2000 immunoassay. Biochemical, hematological parameters, and hormone levels were measured by Beckman-Coulter AU 5800 (Beckman Coulter, Brea, USA), Beckman Coulter LH 780 (Beckman Coulter, Miami, FL, USA), and Cobas 6000 (Roche Diagnostics, Germany) analyzers, respectively.

RESULTS

The imprecision values for all analytes were less than 7.0 %. The correlation coefficient between the methods was 0.981 (95 % confidence interval: 0.975 to 0.985). Linear regression analysis demonstrated highly significant associations of carbamazepine concentrations with albumin (B = -0.300, p = 0.040), calcium (B = -0.262, p = 0.004), phosphorus (B = -0.241, p = 0.022), WBC (B = -0.288, p = <0.001), PLT (B = -0.236, p = 0.003), RBC (B = -0.257, p = 0.001), NEU% (B = -0.289, p = <0.001), LYM% (B = -0.268, p = 0.001), D vitamini (B = -0.344, p = 0.006) levels.

CONCLUSIONS

A robust, rapid, and simple method has been developed. Our study revealed that carbamazepine and its metabolite have a significant correlation and likely impact on bone metabolism, blood cell counts, serum protein, albumin levels, and electrolyte concentrations.