Quantitation of Antiepileptics in Serum by UHPLC-Triple Quadrupole Mass Spectrometry

Significance of the Topic

The management of epilepsy relies on maintaining stable blood concentrations of antiepileptic drugs to prevent seizures and minimize side effects. Therapeutic drug monitoring (TDM) is critical because interindividual variability in drug metabolism can lead to subtherapeutic or toxic levels. A rapid, sensitive method for simultaneous quantitation of multiple antiepileptics in serum supports personalized dosing, improves patient safety, and enhances clinical decision-making.

Objectives and Study Overview

This study aimed to develop and validate a streamlined UHPLC-triple quadrupole MS/MS method for the simultaneous quantitation of 26 antiepileptic compounds in human serum. Key goals included reducing sample volume, shortening analysis time, achieving broad chemical coverage, and meeting regulatory standards for linearity, precision, and accuracy.

Methodology and Instrumentation

The analytical workflow integrates simple protein precipitation with high-throughput UHPLC-MS/MS:

• Sample Preparation: 50 µL serum mixed with 100 µL precipitation reagent containing isotopically labeled internal standards; vortex 30 s; centrifuge 5 min at 10 000 x g; dilute 50 µL supernatant 1:20 with dilution solution.
• UHPLC System: Bruker Elute UHPLC equipped with ClinMass TDM MS9030 column and prefilter MS9032; gradient elution over 4.5 min; flow rate 600 µL/min; injection volume 5 µL; column oven at 40 °C.
• MS/MS Detection: EVOQ LC-TQ Elite with VIP H-ESI source; fast polarity switching to acquire positive and negative ions in one run; collision gas argon at 1.5 mTorr; optimized MRM transitions for each analyte.

Main Results and Discussion

Chromatographic separation of all 26 antiepileptics was achieved in under 4.5 minutes with clear baseline resolution. Calibration employed three concentration levels per analyte giving excellent linearity (R² ranging from 0.9931 to 1.0000). Precision and accuracy were evaluated using low (QC I) and high (QC II) serum quality controls:

• Precision: relative standard deviation below 9% for all compounds except phenytoin (14.3% at QC II).
• Accuracy: bias within ±10% for most analytes; the largest deviation observed was 13.5% for N-desmethylmethsuximide.

The combination of minimal sample requirement (50 µL), straightforward preparation, and rapid UHPLC-MS/MS analysis underlines the method’s suitability for high-throughput TDM applications.

Benefits and Practical Applications

This method offers several practical advantages for clinical and research laboratories:

• High throughput: full panel analysis in a single 4.5 min run accelerates sample turnaround.
• Low sample volume: ideal for pediatric and intensive-care settings.
• Robust performance: strong linearity, precision, and accuracy ensure reliable TDM data.
• Wide coverage: inclusion of diverse antiepileptic classes supports comprehensive monitoring.

Future Trends and Potential Applications

Advancements likely to build on this method include:

• Expansion to emerging antiepileptics and metabolites for more complete therapeutic profiles.
• Automation and on-line sample prep to further increase throughput and reproducibility.
• Integration with clinical informatics for real-time dose adjustment recommendations.
• Adaptation to point-of-care or bedside platforms to expedite urgent TDM results.

Conclusion

The presented UHPLC-triple quadrupole MS/MS assay affords rapid, sensitive, and accurate quantitation of 26 antiepileptics in minimal serum volumes. Its strong analytical performance and streamlined workflow make it a valuable tool for routine therapeutic drug monitoring in clinical and research settings.