Closing the gap — development of an analytical methodology using volumetric absorptive microsampling of finger prick blood followed by LC-HRMS/MS for adherence monitoring of antihypertensive drugs

Abstract

Volumetric absorptive microsampling (VAMS), an emerging microsampling technique, is a promising tool for adherence monitoring. This study focused on development of an analytical methodology to improve VAMS-based strategies for adherence assessment by analyzing angiotensin-converting-enzyme (ACE) inhibitors, loop diuretics, a potassium-sparing diuretic, and a thiazide diuretic. Development included sample preparation, chromatographic conditions, mass spectrometry settings, validation, and demonstrating proof of concept. Quantification of analytes, by name furosemide, hydrochlorothiazide, lisinopril, torasemide, and the active metabolites, canrenone, enalaprilat, and ramiprilat in finger prick blood (FPB), was validated based on international guidelines. Selectivity, carryover, and within/between-run accuracy and precision were in accordance with the recommendations. The matrix effect was evaluated at three different hematocrit levels (HT: 20%, 40%, 60%) and the coefficients of variation did not exceed 15%. Dilution integrity (1:10 and 1:20) was given for all analytes except lisinopril, yet for lisinopril, the therapeutic range was already covered by the calibration range. Long-term stability in VAMS tips was tested for 2 weeks at 24 °C in the dark and revealed no degradation of analytes. The proof of concept was performed by analyzing 35 intakes of ACE-inhibitors and diuretics in 18 VAMS and matched plasma samples. Hereby, determined concentration in FPB and plasma cannot be used interchangeably, and thus specific reference ranges for whole blood must be established. Nevertheless, the VAMS-based strategy was shown to be suitable for assessing adherence of all classes of antihypertensive drugs used in the guidelines to manage hypertension. Graphical abstract

Sample Matrices for Mass Spectrometry–Based Adherence Monitoring: A Systematic Critical Review

“…57 Therefore, several publications proposed to use individual calculated dose-related concentrations or trough concentrations to assess the adherence of a patient. [30][31][32]34,39 In all cases, white coat adherence where patients only take their medication in anticipation of a monitoring event cannot be excluded.…”

“…60 Thus, elucidation of capillary blood-to-plasma concentrations and consideration of the hematocrit levels is necessary. 62,63 Two publications dedicated to the adherence assessment of antiretroviral drugs (ARD), 41,42 2 to cardiovascular drugs, 38,39 and 1 to psychiatric drugs 40 were found. Jacobs et al used dose-related concentrations as cutoff concentrations for adherence assessment and compared the determined concentrations in volumetric absorptive microsampling to matching plasma concentrations.…”

“…A comparison of these concentrations showed that reference ranges defined for plasma cannot be used interchangeably; thus, specific reference ranges for capillary blood must be established. 38,39 Moreover, Luginbühl et al monitored alcohol markers in SUD patients using DBS and compared the results using urine and blood as sample matrices. They observed that the results from venous DBS and capillary DBS were equivalent and that the stability of phosphatidylethanol was lower in liquid blood.…”