Drug Interactions between darolutamide and dexamethasone / moxifloxacin

MONITOR CLOSELY: Concomitant administration of corticosteroids may potentiate the risk of tendinitis and tendon rupture associated with fluoroquinolone treatment. The mechanism is unknown. Tendinitis and tendon rupture have most frequently involved the Achilles tendon, although cases involving the rotator cuff (the shoulder), the hand, the biceps, and the thumb have also been reported. Some have required surgical repair or resulted in prolonged disability. Tendon rupture can occur during or up to several months after completion of fluoroquinolone therapy.

MANAGEMENT: Caution is recommended if fluoroquinolones are prescribed in combination with corticosteroids, particularly in patients with other concomitant risk factors (e.g., age over 60 years; recipient of kidney, heart, and/or lung transplant). Patients should be advised to stop taking the fluoroquinolone, avoid exercise and use of the affected area, and promptly contact their physician if they experience pain, swelling, or inflammation of a tendon. In general, fluoroquinolones should only be used to treat conditions that are proven or strongly suspected to be caused by bacteria and only if the benefits outweigh the risks.

GENERALLY AVOID: Coadministration with potent or moderate inducers of CYP450 3A4 that also induce P-glycoprotein (P-gp) may significantly decrease the plasma concentrations of darolutamide, which is a substrate of both the isoenzyme and the efflux transporter. Reduced efficacy of darolutamide may occur. When darolutamide was coadministered with rifampin, a dual P-gp and potent CYP450 3A4 inducer, mean darolutamide peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 52% and 72%, respectively, compared to administration of darolutamide alone. The decrease in darolutamide exposure by moderate CYP450 3A4 inducers is expected to be in the range of 36% to 58% according to the prescribing information.

MANAGEMENT: Concomitant use of darolutamide with dual P-gp and potent or moderate CYP450 3A4 inducers should generally be avoided.