Development and Validation of a Reverse-Phase High-Performance Liquid Chromatography with Fluorescence Detection (RP-HPLC-FL) Method to Quantify Ruxolitinib in Plasma Samples

Ruxolitinib is a JAK 1/2 inhibitor approved in 2011 by the Food and Drug Administration (FDA) for the treatment of patients with myelofibrosis. Currently, side effects related to the use of ruxolitinib are routinely managed through therapeutic dose adjustment and blood count monitoring. However, the evaluation of plasma concentration of this compound and other tyrosine kinase inhibitors is becoming of increasing importance, since the therapeutic efficacy of this class of drugs is characterized by a marked variability caused by the presence of genetic polymorphisms, drug-drug interactions, and potential poor patient adherence. Therapeutic drug monitoring of these compounds is thus required to ensure both an optimal response and the reduction of potential adverse effects. In this manuscript, we describe the development and validation of a reverse-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of ruxolitinib in plasma, using a liquid chromatographic system equipped with a fluorometric detector (FL) and a mobile phase at pH 4.8 composed of 67:33 water:acetonitrile. The excitation and emission wavelengths were set to 320 nm and 386 nm, respectively. The lower limit of quantification in plasma was 0.1 ng/mL, and the response was linear across the concentration range from 0.2 to 500 ng/mL. The developed methodology, based on a simple extraction procedure and on a rapid chromatographic analysis involving a 5 minutes total analysis time, was validated according to the European Medicines Agency (EMA) guidelines, and may be considered as alternative and complementary to other previously proposed approaches.