Drug Interaction Report

GENERALLY AVOID: Coadministration with erdafitinib may alter the plasma concentrations of drugs that are substrates of the CYP450 3A4 isoenzyme, resulting in increased toxicity or decreased efficacy of these drugs. In vitro, erdafitinib has been shown to be a time-dependent inhibitor as well as inducer of CYP450 3A4. However, no pharmacokinetic data are available from drug interaction studies.

MANAGEMENT: Concomitant use of erdafitinib and sensitive CYP450 3A4 substrates or substrates with narrow therapeutic ranges should generally be avoided.

GENERALLY AVOID: The pharmacologic activity of oral midazolam, triazolam, and alprazolam may be increased if taken after drinking grapefruit juice. The proposed mechanism is CYP450 3A4 enzyme inhibition. In addition, acute alcohol ingestion may potentiate CNS depression and other CNS effects of many benzodiazepines. Tolerance may develop with chronic ethanol use. The mechanism may be decreased clearance of the benzodiazepines because of CYP450 hepatic enzyme inhibition. Also, it has been suggested that the cognitive deficits induced by benzodiazepines may be increased in patients who chronically consume large amounts of alcohol.

MANAGEMENT: The manufacturer recommends that grapefruit juice should not be taken with oral midazolam. Patients taking triazolam or alprazolam should be monitored for excessive sedation. Alternatively, the patient could consume orange juice which does not interact with these drugs. Patients should be advised to avoid alcohol during benzodiazepine therapy.