Effect of fluconazole on the pharmacokinetics of a single dose of fedratinib in healthy adults

Purpose Fedratinib is an orally administered Janus kinase (JAK) 2–selective inhibitor for the treatment of adult patients with intermediate-2 or high-risk primary or secondary myelofibrosis. In vitro, fedratinib is predominantly metabolized by cytochrome P450 (CYP) 3A4 and to a lesser extent by CYP2C19. Coadministration of fedratinib with CYP3A4 inhibitors is predicted to increase systemic exposure to fedratinib. This study evaluated the effect of multiple doses of the dual CYP3A4 and CYP2C19 inhibitor, fluconazole, on the pharmacokinetics of a single dose of fedratinib. Methods In this non-randomized, fixed-sequence, open-label study, healthy adult participants first received a single oral dose of fedratinib 100 mg on day 1. Participants then received fluconazole 400 mg on day 10 and fluconazole 200 mg once daily on days 11–23, with a single oral dose of fedratinib 100 mg on day 18. Pharmacokinetic parameters were calculated for fedratinib administered with and without fluconazole. Results A total of 16 participants completed the study and were included in the pharmacokinetic population. Coadministration of fedratinib with fluconazole increased maximum observed plasma concentration ( C max ) and area under the plasma concentration–time curve from time 0 to the last quantifiable concentration (AUC 0–t ) of fedratinib by 21% and 56%, respectively, compared with fedratinib alone. Single oral doses of fedratinib 100 mg administered with or without fluconazole were well tolerated. Conclusions Systemic exposure after a single oral dose of fedratinib was increased by up to 56% when fedratinib was coadministered with fluconazole compared with fedratinib alone. Trial registry: Clinicaltrials.gov NCT04702464.