2023 · Journal of pharmaceutical and biomedical analysis · paywalled
Determination of lithium concentration in capillary blood using volumetric dried blood spots
Wikström et al.
The finding, in our words
Volumetric dried blood spots from finger-prick correlated strongly with venous serum lithium concentrations (Pearson’s R=0.95, ratio 0.78) in thirty-nine patients. This patient-centric microsampling method could enable home-based therapeutic drug monitoring for bipolar disorder, improving compliance and safety where venous sampling is impractical.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
In AML and CLL, 91% of VAMS venetoclax results fell within 20% of plasma after individualised haematocrit correction; in home sampling, 18 of 21 patients self-sampled independently and 76% of returned samples were analysable, which shows home microsampling is workable, though the authors ask for multicentre validation.
This review found that volumetric microsampling devices, such as Mitra, HemaPEN, HemaXis DB10, and Tasso-M20, overcome haematocrit bias, whilst Telimmune plasma separation cards enable direct plasma collection without centrifugation. These technologies support patient-centric, decentralised sampling, though the authors note that clinical validation remains limited across different drugs and patient populations.
Volumetric microsampling can enable patient-centred therapeutic drug monitoring with high patient preference and acceptable method validation for many drugs, but conversion from capillary to plasma and agreement with venous sampling varies by analyte and requires careful validation.
Microsampling, particularly VAMS and quantitative DBS, can enable patient-centric therapeutic drug monitoring of immunosuppressants after transplantation, allowing home self-sampling and long-term monitoring when patients live far from transplant centres. These volumetric dried formats have largely overcome the haematocrit effect and sample heterogeneity that limit conventional dried blood spots.
Clinical validation for tacrolimus and mycophenolic acid monitoring showed that while volumetric absorptive microsampling met analytical criteria after concentration correction, conventional dried blood spots achieved superior adherence to strict clinical criteria, sample quality, and cost efficiency without significant haematocrit bias.