Evaluation and analytical applicability of a novel volumetric absorptive microsampling strategy for adherence monitoring of antihypertensive drugs by means of LC-HRMS/MS.

Volumetric absorptive microsampling (VAMS), an emerging microsampling technique, is expected to overcome some disadvantages of dried blood spots. This study aimed to develop and evaluate a VAMS-based strategy for quantifying ten frequently prescribed antihypertensive drugs (AHD) (amlodipine, bisoprolol, candesartan, carvedilol, lercanidipine, losartan carboxylic acid, metoprolol, nebivolol, telmisartan, valsartan) in finger prick blood (FPB) within the scope of adherence monitoring. The straightforward workflow consisted of VAMS tip hydration and subsequent precipitation. Samples were analyzed by using reversed phase ultra-high performance liquid chromatography coupled to orbitrap mass spectrometry operating in parallel reaction monitoring mode. The analytical procedure was successfully validated based on international recommendations for most of the analytes. Selectivity and within/between-run accuracy and precision were in accordance with the recommendations. Internal standard normalized matrix factor met recommended criteria for all analytes at HT 20%, 40%, and 60% except for amlodipine were the CV exceeded 15% at HT 20% (CV 18%). Dilution integrity was given for all substances, covering the quantification in the upper part of the therapeutic range of selected AHD. Long-term stability in VAMS tips was tested and revealed degradation of lercanidipine after one week of storage at 24 °C. A proof of concept of the analytical applicability was done by quantification of selected AHD in VAMS tips and matched plasma samples. Results revealed that determined concentration in FPB by VAMS and plasma cannot be used interchangeably, and thus that specific reference ranges have to be established. However, a novel VAMS application was implemented in the context of adherence monitoring for at least the investigated AHD.