Applications of Volumetric Absorptive Microsampling Technique: A Systematic Critical Review

Background:Microsampling is a technique that utilizes a very small volume of biological matrix, typically less than 50 & mu;L, for quantitatively analyzing chemicals, drugs, and biologics. The use of filter paper for blotting blood samples, usually referred to "Dried Blood Spots", is an example of a microsampling approach, which has been established since the early 1960s. However, non-homogeneous sample spread, the influence of hematocrit, improper volume measurement, and environmental degradation are major bottlenecks to the widespread adoption of this technique in routine clinical sample analysis. Novel methods have overcome several of these issues; however, assays using these microsampling tools involve variable steps/approaches.Methods:A novel microsampling device called Volumetric Absorptive microsampling (VAMS), developed in 2014, appears to have resolved the sample inhomogeneity inherent to dried blood spots, with improved precision in the volume of sample collected for measuring drug concentration. A literature search was conducted to identify several analytical and pharmacokinetic studies that have used VAMS in recent years.Results:The key factors for proper experimental design and optimization of the extraction of drugs and metabolites of interest from the device were summarized. This review focuses on VAMS and elaborates on bioanalytical factors, method validation steps, and scope of this technique in clinical practice.Conclusions:The promising microsampling method VAMS is especially suited for conducting pharmacokinetic studies with very small volumes of blood, especially in special patient populations. Clinical validation of every VAMS assay must be conducted prior to the routine practical implementation of this method.