26 Lug A simple high performance liquid chromatography-mass spectrometry method for Therapeutic Drug Monitoring of isavuconazole and four other antifungal drugs in human plasma samples.

Invasive fungal infections treatment is afforded by triazoles, whose pharmacokinetic properties are still partially unclear. In particular, isavuconazole (ISC) is a new broad-spectrum antifungal triazole approved in 2015 as first-line treatment for intravenous and oral use against invasive aspergillosis and for mucormycosis. Optimal management of triazoles requires the use of Therapeutic Drug Monitoring (TDM), in order to prevent sub-therapeutic or toxic concentrations. The aim of this work was the development and full validation of a HPLC-mass spectrometry assay for simultaneous quantification of fluconazole, itraconazole, isavuconazole, posaconazole and voriconazole in human plasma samples, following FDA (Food and Drug Administration) and EMA (European Medicines Agency) guidelines. Simple protein precipitation with acetonitrile and dilution with water were performed. Chromatographic separation was performed on Atlantis® T3 5µm 4.6 x 150mm column, with a gradient of water and acetonitrile, both added with 0.05% formic acid. All tested parameters (accuracy, intra-day and inter-day precision, matrix effects and recoveries) resulted in accordance to guidelines. Finally, we tested this method by monitoring plasma concentrations in real patients and using external quality controls with excellent results. This method resulted very simple, fast, cheap and very useful for TDM application, to improve clinical management of antifungal therapy in critically ill patients.