Assessing pharmacokinetics and drug-drug interactions of the combination therapy of myelofibrosis with ruxolitinib and lenalidomide by a new eco-friendly HPLC method for their simultaneous determination in plasma.

Ruxolitinib (RUX), a Janus kinase 2 (JAK2) inhibitor, and lenalidomide (LEN), an immunomodulatory agent, have recently been proposed as a combined treatment for myelofibrosis (MF). This combination has demonstrated improved efficacy, safety, and tolerability compared to monotherapy. To further refine these findings, an efficient analytical tool is needed to simultaneously determine RUX and LEN concentrations in blood plasma. This tool would enable the study of their pharmacokinetics, drug-drug interactions, and therapeutic monitoring during MF therapy. Unfortunately, such a method has not been existed in the literature. This study presents the first HPLC method with UV detection for the simultaneous quantitation of RUX and LEN in plasma. The method was validated according to the ICH guidelines for bioanalytical method validation. It exhibited linearity in the concentration ranges of 10 to 3150 ng mL for RUX and 80 to 5200 ng mL for LEN. The limits of quantitation were determined to be 25 and 90 ng mL for RUX and LEN, respectively. All other validation parameters were satisfactory. The HPLC-UV method was successfully employed to study the pharmacokinetics and drug-drug interactions of RUX and LEN in rats following oral administration of single doses. The results demonstrated that the pharmacokinetics of both drugs were changed substantially by their coadministration. LEN exhibited synergistic effects on the maximum plasma concentration (C) and total bioavailability of RUX, meanwhile it exhibited diminishing effect on the values of volume of distribution (Vd) and clearance (CL). Additionally, RUX decreased the C and total bioavailability of LEN, meanwhile it increased its Vd and CL. These data suggest that the use of RUX, as a combination with LEN, is a better therapeutic approach for MF, compared with RUX as a monotherapy. The effects of LEN on the pharmacokinetics of RUX should be considered and can be useful in determining the appropriate RUX dosage and dosing regimen to achieve the desired therapeutic effect when used as a combination therapy with LEN. The method's environmental friendliness was confirmed through three comprehensive tools. This method represents a valuable tool for determining the appropriate dosage and dosing regimen of RUX in combination therapy with LEN to achieve the desired therapeutic effect. Furthermore, it can aid in predicting drug distribution in different patients and assessing the drug accumulation or insufficient drug levels in specific body compartments.