Drug Interactions between conivaptan and erdafitinib

GENERALLY AVOID: Coadministration of erdafitinib with potent inhibitors of CYP450 2C9 or 3A4 may increase the plasma concentrations and risk of toxicity of erdafitinib, which is a substrate of these isoenzymes. When coadministered with fluconazole, a strong CYP450 2C9 inhibitor and moderate CYP450 3A4 inhibitor, erdafitinib mean ratios for Cmax and AUC were 121% and 148%, respectively, relative to erdafitinib alone. Similarly, when coadministered with itraconazole, a strong CYP450 3A4 inhibitor, erdafitinib mean ratios for Cmax and AUC were 105% and 134%, respectively, relative to erdafitinib alone.

MANAGEMENT: Coadministration of erdafitinib with potent inhibitors of CYP450 2C9 or 3A4 should generally be avoided. If concomitant use is unavoidable, patients should be closely monitored for the development of adverse effects. Dosage adjustments as well as clinical and laboratory monitoring of erdafitinib should be considered whenever a CYP450 2C9 or 3A4 inhibitor is added to or withdrawn from therapy.