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

Microsampling with Mitra® devices correlated strongly with venous plasma for capecitabine therapeutic drug monitoring (r=0.97), but yielded consistently lower concentrations. Patients preferred this method and reported minimal pain, suggesting it is suitable for patient-centric oncology drug monitoring in decentralised settings.

Comparison of capecitabine concentrations determined by microsampling versus plasma concentrations for therapeutic drug monitoring: a pilot study — Shafiei et al., The Journal of pharmacy and pharmacology (paywalled) · source ↗

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

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

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

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.

Clinical Validation of Venetoclax Volumetric Microsampling in Leukemia, with Whole-Blood-to-Plasma Conversion and Self-Microsampling Feasibility — Levens et al., Clinical Pharmacokinetics (paywalled) · source ↗

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

An LC-MS/MS method for tamoxifen and six metabolites in VAMS was developed and validated, with water prerinsing improving recoveries and poor room temperature stability but stability for at least 100 days at minus 80 degrees Celsius. Plasma to blood ratios were used to estimate plasma equivalent concentrations, and paired VAMS and plasma samples from ten breast cancer patients showed strong correlations and good agreement on Bland-Altman analysis, supporting reliable decentralised TDM.

Development and validation of an LC-MS/MS method for the comprehensive quantification of tamoxifen and its metabolites in volumetric absorptive microsampling: clinical application in breast cancer patients — Kuo et al., Analytical and bioanalytical chemistry (paywalled) · source ↗

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