High-Throughput In Vitro ADME Analysis with Agilent RapidFire/MS Systems: Permeability Assays

Significance of the Topic

Permeability assays such as Caco-2 and PAMPA are fundamental in early drug discovery to predict oral absorption of new chemical entities. Optimizing throughput and data quality in these in vitro ADME assays accelerates decision making and reduces costs by enabling rapid screening of large compound libraries.

Study Objectives and Overview

This work aimed to evaluate the performance of the Agilent RapidFire high-throughput mass spectrometry platform coupled with either a triple quadrupole (QQQ) or a quadrupole-time-of-flight (Q-TOF) analyzer. Two series of experiments were conducted:

• PAMPA assays on 81 proprietary drug candidates at pH 4, 6.8 and 8 to compare RapidFire/TOF with conventional LC/MS/MS permeability values.
• Caco-2 and PAMPA assays to correlate apparent permeability coefficients (PAPP) between RapidFire/MS/MS and validated LC/MS/MS methods across 110 and 35 experiments, respectively.

Methodology

PAMPA assays used a generic solid-phase extraction (SPE) method with RapidFire/TOF, eliminating the need for compound-specific multiple reaction monitoring (MRM) optimization. Caco-2 assays generated basolateral samples for PAPP determination. Sample cycle times on RapidFire ranged from six to ten seconds, representing a >10-fold speed gain compared to conventional LC/MS/MS workflows.

Instrumentation Used

• Agilent RapidFire high-throughput SPE/MS system
• Agilent 6430 or 6495 triple quadrupole mass spectrometer (QQQ)
• Agilent 6530 or 6545 quadrupole-time-of-flight mass spectrometer (Q-TOF)
• Parallel artificial membrane permeation assay (PAMPA) and Caco-2 cell culture setups

Main Results and Discussion

RapidFire/TOF permeability values correlated strongly with LC/MS/MS data across pH conditions:

• pH 4: R² ≈ 0.89
• pH 6.8: R² ≈ 0.74
• pH 8: R² ≈ 0.83

Caco-2 PAPP coefficients (110 samples) showed an excellent correlation (R² = 0.969) between RapidFire/MS/MS and validated LC/MS/MS. PAMPA PAPP values (35 samples) also aligned well (R² = 0.891), covering low, medium and high permeability ranges. The ultra-fast SPE/MS workflow maintained data integrity while reducing per-sample analysis time dramatically.

Benefits and Practical Applications of the Method

• Throughput increased by more than ten-fold compared to traditional LC/MS/MS.
• Elimination of compound-specific MRM optimization accelerates method setup.
• Reduction in solvent and consumable usage lowers operating costs.
• Seamless integration into existing ADME screening pipelines for rapid permeability ranking.

Future Trends and Potential Applications

High-throughput SPE/MS platforms can be extended to other ADME assays such as metabolic stability, protein binding and enzymatic screening. Integration with automated sample preparation, cloud-based data analysis and machine learning models will further enhance predictive power and lab efficiency. Miniaturization of assays and multiplexed workflows may enable screening of ever-larger compound collections with minimal sample consumption.

Conclusion

The Agilent RapidFire high-throughput mass spectrometry system, when interfaced with QQQ or Q-TOF instruments, delivers equivalent permeability data to conventional LC/MS/MS methods while offering a ten-fold improvement in sample throughput. This approach streamlines early ADME screening, reduces costs and supports faster decision making in drug discovery.

References

• Hatsis, P., et al. Reducing Bottlenecks in ADME Sample Analysis using Solid Phase Extraction with a Quadrupole Time-of-Flight Mass Spectrometer. Podium talk by Novartis/Biocius at the 2010 ASMS meeting.
• Luippold, A., et al. Application of a Rapid and Integrated Analysis System (RIAS) as a High-Throughput Processing Tool for In Vitro ADME Samples by Liquid Chromatography/Tandem Mass Spectrometry. J. Biomol. Screen 2011, 16(3), 370–377.