Adherence to cardiovascular pharmacotherapy assessed by quantitative LC-HRMS analysis of dried blood spots

Up to ~50% of patients prescribed cardiovascular (CVD) drugs do not adhere to their prescribed regimen. Non-adherence impacts on patient health and healthcare system costs. Dried blood spot (DBS) sampling was used to collect micro-volume blood samples for the LC-HRMS quantitative analysis of candidate CVD drugs for objectively assessing adherence to prescribed pharmacotherapy. An LC-HRMS method was used for the quantification of target CVD drugs in DBS samples. The target CVD drugs were solvent extracted from disks punched from DBS and analysed using gradient chromatographic elution with a run time of 2.5 min. MS detection was carried out in electrospray positive ion mode using the precise mass for each target drug. The method was applied to volunteer DBS samples. Drug recoveries from spiked calibration blood spots were ≥82% for all target CVD drugs except for simvastatin at ~57% and the drugs were stable in DBS for at least 12 weeks. Validation of the LC-HRMS method showed good linearity and the accuracy and precision values were within the pre-defined limits of ≤15% at all concentrations. Factors with potential to affect drug quantification measurements such as matrix effects and the volume of blood applied on the collection card were investigated. This bioanalytical method was able to identify and quantify the residual levels of target drugs up to 24 hours after the initial dose. The LC-HRMS DBS based assay successfully identified volunteers who were known to be either adherent or nonadherent.