Drug Interaction Report

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of pimavanserin, which is primarily metabolized by the isoenzyme. A drug interaction study has shown decreases in pimavanserin Cmax (71%) and AUC (91%) with coadministration of rifampin, a strong CYP450 3A4 inducer. A physiologically based pharmacokinetic simulation with a moderate CYP450 3A4 inducer (efavirenz) predicted Cmax and AUC of pimavanserin will be decreased by approximately 60% and 70%, respectively.

MANAGEMENT: The possibility of diminished therapeutic response to pimavanserin should be considered during coadministration with CYP450 3A4 inducers. The manufacturer recommends coadministration with strong or moderate CYP450 3A4 inducers be avoided.

MONITOR: Isolated case reports have suggested that the ingestion of alcohol during griseofulvin therapy may rarely cause disulfiram-like reactions, flushing, tachycardia, or increased effects of alcohol. The mechanism is unknown.

MANAGEMENT: Patients should be advised of the possibility of increased adverse effects or a disulfiram-like reaction.