Therapeutic Drug Monitoring of Antiseizure Medications Using Volumetric Absorptive Microsampling: Where Are We?

Abstract

Therapeutic drug monitoring (TDM) of antiseizure medications (ASMs) represents a valuable tool to establish an appropriate patient therapy, to collect important information about drugs’ interactions and to evaluate patient’s metabolic capabilities. In recent years, a new volumetric absorptive microsampling technique using VAMS® technology and Mitra® devices, consisting of a sampling technique for the collection of fixed-volume capillary blood, was developed. These new devices provide a new home-sampling technique for whole blood that has been spread out to simplify sample collection from finger-pricks. This review is aimed to compare published articles concerning the application of VAMS® in epilepsy and to identify the strengths and improvement points for the TDM of antiseizure medications. VAMS® allowed a minimally invasive blood sampling even in the absence of trained personnel. Good stability data have indicated that storage and delivery can be facilitated only for specific ASMs. Trueness and precision parameters have been evaluated, and the hematocrit (HCT) effect was minimized.

Pharmacological aspects of antiseizure medications: From basic mechanisms to clinical considerations of drug interactions and use of therapeutic drug monitoring

“…[77][78][79][80] Volumetric absorptive microsampling is another technique successfully applied to monitor ASMs. 81,82 These devices are porous hydrophilic tips that allow the collection of a small, fixed blood volume (10 or 30 μL) avoiding hematocrit bias. [82][83][84] Further advances in the clinical validation of these methods are needed, as analytical errors can result in inappropriate clinical decisions, and patient correlation studies are scarce.…”

“…This approach has been implemented for many ASMs, but there are still technical issues needing improvement 77–80 . Volumetric absorptive microsampling is another technique successfully applied to monitor ASMs 81,82 . These devices are porous hydrophilic tips that allow the collection of a small, fixed blood volume (10 or 30 μL) avoiding hematocrit bias 82–84 .…”

Volumetric Absorptive Microsampling to Enhance the Therapeutic Drug Monitoring of Tacrolimus and Mycophenolic Acid: A Systematic Review and Critical Assessment

“…Compared with previous summaries of VAMS in other therapeutic areas, a unique feature of this review is the inclusion of all factors necessary for implementing VAMS in clinical care. [23][24][25] These factors include home-based sampling, AUC estimation, trough monitoring, patient-reported outcomes, and cost. A critical assessment was made of the relevant evidence to identify opportunities to strengthen the potential implementation of VAMS-based TDM in transplant care.…”

Microsampling with a Solid-Phase Extraction Cartridge: Storage and Online Mass Spectrometry Analysis

“…For example, precut DBSs (PCDBSs) can reduce the hematocrit effect, improve sample utilization, and minimize carryover issues between the punches . Volumetric absorptive microsampling (VAMS) overcomes hematocrit effects by collecting precise volumes of the biofluid into an absorbent tip with reproducible internal porous volume. , Recently, the biofluid sampler approach was introduced, where the cellulose fabric substrate is coated with porous sol–gel sorbents to decrease the maximum sample volume, reduce the hematocrit effect, and improve physical adsorption of the sample . Like the traditional DMS microsampling methods, these new methods also require several hours of drying in ambient air, as well as are subject to dilution since several steps are required to recover and extract analytes for offline analysis.…”