Drug Interaction Report

MONITOR: Coadministration with enzalutamide may decrease the plasma concentrations of drugs that are substrates of CYP450 3A4, 2C9, 2C19, and/or P-glycoprotein (P-gp) efflux transporter. The proposed mechanism involves accelerated clearance via these routes due to enzalutamide-mediated induction. The resulting plasma concentrations will depend on the sensitivity of the affected drugs to these isoenzymes.

MANAGEMENT: Caution is advised when enzalutamide is used concomitantly with drugs that are substrates of CYP450 3A4, 2C9, 2C19, and/or P-gp, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever enzalutamide is added to or withdrawn from therapy.

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.