Volumetric Absorptive Microsampling in Therapeutic Drug Monitoring of Immunosuppressive Drugs—From Sampling and Analytical Issues to Clinical Application

Abstract

Miniaturisation and simplification are novel approaches in clinical bioanalysis, especially in therapeutic drug monitoring (TDM). These contemporary trends are related to the sampling, pre-treatment, and analysis of biological fluids. Currently, dried blood spot (DBS), one of the most popular microsampling techniques, is feasible and inexpensive. However, obtaining reliable results with sample homogeneity and volume variability is difficult. Volumetric Absorptive Microsampling (VAMS) has recently enabled the accurate and precise collection of a fixed blood volume. It reduced the hematocrit effect, improved volumetric accuracy, and generated results correlating with the dose and drug exposure from wet blood. This review focuses on VAMS-Mitra™ devices, which have become increasingly important since 2014, mainly for TDM and toxicology studies. First, the current literature has been reviewed based on immunosuppressants and their determination in samples obtained using Mitra™. Second, the critical points, weaknesses, and strengths have been characterized in contrast to classic venipuncture and other microsampling methods. Finally, we indicate the points of attention according to the perspective of Mitra™ as well as its usefulness in clinical practice. VAMS is currently state-of-the-art in microsampling and seems to be a good instrument for improving adherence to immunosuppressive therapy, especially in the pediatric population.

Volumetric Absorptive Microsampling Technique in the LC-MS Determination of Direct Oral Anticoagulants

“…In addition, the introduction of the VAMS technique in routine TDM enables to increase in the adherence of the patients to the therapy, as it allows home sampling without the assistance of trained personnel. Dried Mitra sticks can be delivered to the laboratory, packed in envelopes, and sent via standard postal services [26]. Moreover, several authors using the questionnaire forms confirmed that VAMS home sampling is preferred over traditional blood sampling in the case of routine monitoring [27,28].…”

Biological Fluid Microsampling for Therapeutic Drug Monitoring: A Narrative Review

“…Microsampling offers several practical advantages over traditional samples, such as minimal invasiveness for patients and simplified logistical requirements. Although equivalence with or without correction factors has been demonstrated in many cases [5][6][7][8][9], it is necessary to validate drug-specific reference/target ranges for each microsampling device. In fact, because of possible differences in the drug concentrations among alternative matrices (capillary blood, urine, breast milk, saliva) [10] and possible interactions of analytes with filtration or adsorption materials, which must be evaluated during method development [11], the reference/target ranges established for TDM in plasma cannot be transferred directly to microsamples [12].…”

Therapeutic Drug Monitoring of Tacrolimus Based on Volumetric Absorptive Microsampling Technique (VAMS) in Renal Transplant Pediatric Recipients—LC-MS/MS Method Development, Hematocrit Effect Evaluation, and Clinical Application

“…In our recently published review study, the currently developed methods for immunosuppressants determination (including TAC) in VAMS samples were prescribed [ 11 ]. Based on that, the main advantages of the VAMS LC-MS/MS method developed in that study are: the shortest time of sampler drying (1 h) and analytical run (5 min), simple extraction solvent (water), and finally, hematocrit evaluation and clinical cross-validation.…”