Comparison of capecitabine concentrations determined by microsampling versus plasma concentrations for therapeutic drug monitoring: a pilot study

This study established conversion methods for estimating plasma concentrations from whole blood VAMS samples for seven out of ten oral anticancer drugs, finding good agreement between capillary and venous samples. Patients reported a positive experience with home sampling using this microsampling technique.

Clinical Application of Volumetric Absorptive Microsampling for Therapeutic Drug Monitoring of Oral Targeted Anticancer Drugs — Meertens et al., Therapeutic drug monitoring · source ↗

• vams
• volumetric
• venous-agreement
• acceptability
• blood
• tdm
• self-collection
• dried
• oncology
• capillary
• validation

VAMS matched serum for the kinase inhibitors nilotinib, cabozantinib, dabrafenib and ruxolitinib, r 0.94–0.97, with serum reliably predictable for the first three, and 93% of at-home samples were collected correctly: at-home VAMS shown feasible for routine cancer-drug monitoring.

Clinical validation and feasibility of VAMS for monitoring of nilotinib, cabozantinib, dabrafenib, trametinib and ruxolitinib — Zimmermann et al., J. Pharmaceutical and Biomedical Analysis (paywalled) · source ↗

• vams
• venous-agreement
• acceptability
• blood
• tdm
• self-collection
• haematocrit
• dried
• oncology
• capillary
• validation

Capillary blood collected with the Mitra® device showed correlation with venous samples for paclitaxel therapeutic drug monitoring, but wide confidence intervals suggest the methods may not be interchangeable. While plasma and whole blood concentrations were more closely aligned, the variability raises questions about using self-collected capillary samples for dose individualisation without further validation.

Paclitaxel and Therapeutic Drug Monitoring with Microsampling in Clinical Practice — Radovanovic et al., Pharmaceuticals · source ↗

• blood
• liquid
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• venous-agreement
• tdm
• oncology

The authors validated an LC-MS and LC-MS/MS method for quantifying axitinib from 10 microlitre capillary blood collected by VAMS, demonstrating within- and between-run precision within 14% CV and accuracy between 81 and 116% against plasma as the gold standard, making the approach suitable for therapeutic drug monitoring in ambulatory and clinical care.

Development and validation of a bioanalytical method for the quantification of axitinib from plasma and capillary blood using volumetric absorptive microsampling (VAMS) and on-line solid phase extraction (SPE) LC-MS — Opitz et al., Journal of pharmaceutical and biomedical analysis (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• venous-agreement
• tdm
• oncology

Volumetric absorptive microsampling (VAMS) using the Neoteryx Mitra device was validated for mitotane therapeutic drug monitoring across 1–50 mg/L, with acceptable haematocrit bias and one-week stability at room temperature. However, comparison with venous plasma showed poor correlation, suggesting home-based VAMS is of limited clinical value for mitotane unless a method-specific target range is established.

A method for the minimally invasive drug monitoring of mitotane by means of volumetric absorptive microsampling for a home-based therapeutic drug monitoring — Friedl et al., Analytical and bioanalytical chemistry (paywalled) · source ↗

• vams
• venous-agreement
• neoteryx-mitra
• blood
• tdm
• haematocrit
• dried
• oncology
• capillary
• validation