Volumetric absorptive microsampling (VAMS) coupled with high-resolution, accurate-mass (HRAM) mass spectrometry as a simplified alternative to dried blood spot (DBS) analysis for therapeutic drug monitoring of cardiovascular drugs

Here, volumetric absorptive microsampling (VAMS), used for the measurement of cardiovascular drugs, is compared against conventional dried blood spot (DBS) card sampling to evaluate adherence to prescribed medication. Volumetric absorptive microsampling (VAMS) is an attractive alternative to plasma sampling for routine drug monitoring and potentially overcomes haematocrit issues associated with quantitative bioanalysis of conventional dried blood spots. A quantitative VAMS-based LC-HRAM MS assay for atenolol, lisinopril, simvastatin and valsartan was developed and validated. The assay demonstrated acceptable linearity, selectivity, accuracy, precision, recovery and insignificant matrix effects with no impact of haematocrit on assay accuracy. Volunteers provided both VAMS and DBS 903 card samples (the current standard) to allow comparison of the two methods and demonstrate the potential utility of VAMS. Analysis of VAMS samples correctly identified drugs in volunteers known to be adherent, and found no false positives from volunteers known to be taking no medication. There was a strong correlation between the two sampling systems confirming the utility of VAMS. Therapeutic drug monitoring (TDM) can assist clinicians in deciding how to proceed with treatment in the event of poor improvement in patient health. VAMS could offer a potentially more efficient method of sample collection, with fewer rejected samples than the DBS approach.