Collection of trace blood using dedicated device and simultaneous analysis of immunosuppressive drugs in whole blood samples

Importance of the Topic

The precise measurement of immunosuppressive drug levels in blood is essential to balance therapeutic efficacy and minimize adverse effects such as infection or organ rejection. Traditional venous sampling can be invasive and requires larger volumes, limiting frequent monitoring. Microsampling offers a minimally invasive alternative, enabling small-volume sampling from the fingertip while maintaining analytical performance.

Study Objectives and Overview

This work aimed to validate a combined approach using a dedicated trace-blood collection device (Microsampling Wing™) and a LC–MS/MS assay for simultaneous quantification of six immunosuppressants—mycophenolic acid (MPA), mycophenolic acid glucuronide (MPAG), everolimus, sirolimus, tacrolimus, and cyclosporin A—in whole blood. The study compared microsampling results with conventional venous collection and medical record values.

Methodology and Instrumentation

• Sample collection: Approximately 2.8 µL whole blood obtained from fingertip using Microsampling Wing and from venous draw.
• Calibration and QC: Six concentration levels prepared in whole blood matrix; QC samples spiked using DOSIMMUNE™ and DOSIMYCO™ kits.
• Instrumentation: Shimadzu Nexera™ X3 UHPLC coupled to LCMS-8050 mass spectrometer.
• Chromatography: DOSIMMUNE trap and analytical columns; mobile phases A/B (DOSIMMUNE); 0.8 mL/min flow; 65 °C column temperature; 20 µL injection.
• Detection: ESI negative mode for MPA/MPAG and positive mode for the other four drugs; MRM transitions monitored for each analyte and corresponding internal standards.

Key Results and Discussion

• Calibration curves exhibited excellent linearity (R² > 0.99) across all analytes.
• Sixfold repeatability tests on QC samples confirmed that measured concentrations fell within predefined reference ranges.
• Comparative analysis showed strong correlation between microsampled fingertip blood, venous samples, and clinical record values (slopes ~0.9–1.0; R² > 0.94).
• The microsampling method demonstrated accuracy and precision equivalent to standard venous collection with minimal sample volume.

Benefits and Practical Applications

This approach significantly reduces patient discomfort and blood volume requirements, facilitating more frequent therapeutic drug monitoring in outpatient and home-care settings. The integration of microsampling with rapid LC–MS/MS analysis streamlines laboratory workflows and enhances patient compliance.

Future Trends and Applications

Advances may include integration with point-of-care devices, automation of microsample handling, and extension to additional biomarkers or therapeutic drug classes. Remote monitoring and telemedicine applications could further improve personalized dosing regimens.

Conclusion

The validated microsampling-LC–MS/MS method offers a reliable, low-volume strategy for simultaneous quantification of six immunosuppressants. The strong agreement with conventional methods and clinical records supports its adoption for routine therapeutic drug monitoring.

References

• Goda T, Suzuki Y, Masuda J, Kimura N, Aizawa K. Collection of trace blood using dedicated device and simultaneous analysis of immunosuppressive drugs in whole blood samples. Shimadzu Corporation, 2023.