Related Experiment Video
Updated: Jan 5, 2026
08:38
Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS
Published on: November 8, 2015
17.4K
Transition of Methotrexate Polyglutamate Drug Monitoring Assay from Venipuncture to Capillary Blood-Based Collection
Kelley Brady1, Ying Qu1, Deborah Stimson1
1Exagen Diagnostics Inc., Vista, CA.
The Journal of Applied Laboratory Medicine
|October 23, 2019
Summary
Fingerstick collection of capillary blood provides reliable Methotrexate polyglutamate (MTXPG3) levels for guiding rheumatoid arthritis treatment, simplifying therapeutic drug monitoring.
Area of Science:
- Pharmacology
- Clinical Chemistry
- Rheumatology
Background:
- Methotrexate (MTX) polyglutamate (MTXPG3) levels in red blood cells (RBCs) are crucial for optimizing MTX dosing in rheumatoid arthritis (RA).
- Current methods rely on venipuncture for RBC collection, posing a barrier to frequent monitoring.
Purpose of the Study:
- To validate a novel assay for MTXPG3 measurement in dried capillary blood obtained via fingerstick.
- To establish the comparability of fingerstick-derived MTXPG3 levels with traditional venipuncture methods for therapeutic drug monitoring (TDM).
Main Methods:
- Dried capillary blood and venous blood specimens were collected from RA patients on MTX therapy.
- MTXPG3 levels were quantified using LC-MS/MS and converted to RBC equivalents.
- Comparisons were made between fingerstick and venipuncture methods using statistical tests.
Main Results:
- The fingerstick assay demonstrated good precision (2.0%–10.9% intraday, 3.1%–10.8% interday).
- MTXPG3 levels from dried capillary blood closely correlated with those from isolated RBCs (R2 = 0.92).
- Large-scale clinical implementation showed comparable MTXPG3 levels between fingerstick and venipuncture methods (P = 0.09).
Conclusions:
- Dried capillary blood collected by fingerstick is a viable alternative for MTXPG3 TDM in RA patients.
- This method simplifies blood collection, potentially improving patient adherence and treatment outcomes.
Related Concept Videos
01:26Therapeutic Drug Monitoring: Drug Analysis Methods
150
Therapeutic Drug Monitoring (TDM) is a clinical practice that measures specific drug levels in a patient's blood or body tissues to tailor drug therapy effectively. This monitoring is critical for managing drugs with narrow therapeutic indices like digoxin and phenytoin, ensuring they are both safe and effective. For instance, monitoring theophylline levels in asthma patients involves precision and sensitivity to adjust doses according to individual responses to therapy, ensuring efficacy and...
150
01:29Therapeutic Drug Monitoring: Affecting Factors
158
Therapeutic Drug Monitoring (TDM) is the clinical practice of measuring specific drug levels in a patient's blood or body tissues to manage and optimize therapy. TDM is crucial for drugs with narrow therapeutic windows, like warfarin and phenytoin, where incorrect doses can lead to treatment failure or severe side effects. This monitoring ensures the dosage administered is within a safe and effective range. The factors affecting therapeutic drug monitoring include:Patient-Specific Factors:a.
158
01:22Effect of Hepatic Disease on Pharmacokinetics: Pathophysiologic Assessment and Liver Function Test
154
In clinical practice, the direct measurement of hepatic blood flow to evaluate liver function presents significant challenges due to the intricate and specialized nature of the necessary techniques. Consequently, healthcare professionals often rely on empirical estimates derived from thorough patient examinations and liver function tests to gauge liver health. Among the tools at their disposal, the Child–Pugh and MELD scoring systems stand out for their ability to categorize and assess...
154