Therapeutic drug monitoring (TDM) can improve clinical care when using drugs with pharmacokinetic variability and a narrow therapeutic window. Rapid, reliable and easy to use detection methods are required in order to decrease the time of analysis, and can enable TDM also in resource-limited settings or even at bedside. Monitoring methotrexate (MTX), an anti-cancer drug, is critical, since it is needed to follow the drug clearance rate and decide how to administer the rescue drug, leucovorin (LV), in order to avoid toxicity and even death. We show that with the optimized nanopillar assisted separation (NPAS) method using surface-enhanced Raman scattering (SERS) we were able to measure MTX in PBS and serum in the linear range of 5 to 150 µM and confirmed that MTX detection can be carried out even in the presence of LV. Additionally, when NPAS was combined with centrifugal filtration a quantification limit of 2.1 µM for MTX in human serum sample was achieved. The developed detection method enables fast detection (10 min) and quantification of MTX from human serum (>90% accuracy). Furthermore, we show the potential of the developed method for TDM, when quantifying MTX from clinical samples, collected from patients, who are undergoing high-dose MTX therapy.

Therapeutic drug monitoring (TDM) is an essential clinical practice for optimizing drug dosing, thereby preventing adverse effects of drugs with a narrow therapeutic window, slow clearance, or high interperson pharmacokinetic variability. Monitoring methotrexate (MTX) during high-dose MTX (HD-MTX) therapy is necessary to avoid potentially fatal side effects caused by delayed elimination. Despite the efficacy of HD-MTX treatment, its clinical application in resource-limited settings is constrained due to the relatively high cost and time of analysis with conventional analysis methods. In this work, we developed (i) an electrochemically assisted surface-enhanced Raman spectroscopy (SERS) method for detecting MTX in human serum at a clinically relevant concentration range and (ii) a benchtop, Raman detection system with an integrated potentiostat, software, and data analysis unit that enables mapping of small areas of SERS substrates and quantitative SERS-based analysis. In the assay, by promoting electrostatic attraction between gold-coated nanopillar SERS substrates and MTX molecules in aqueous samples, a detection limit of 0.13 μM with a linear range of 0.43−2 μM was achieved in PBS. The implemented sample cleanup through gel filtration proved to be highly effective, resulting in a similar detection limit (0.55 μM) and linear range (1.81−5 μM) for both PBS and serum. The developed and optimized assay could also be used on the in-house built, Raman device. We showed that MTX detection can be carried out in less than 30 min with the Raman device, paving the way toward the TDM of MTX at the pointof-need and in resource-limited environments.

No abstract

No abstract