Drug Interactions between Duzallo and pimavanserin

MONITOR: Coadministration with alcohol or other central nervous system (CNS) depressants may enhance the sedative effects of allopurinol and increase the likelihood and/or severity of central nervous system (CNS) side effects, such as drowsiness, somnolence, vertigo, and ataxia.

MANAGEMENT: Caution for increased CNS adverse effects is advised if allopurinol is coadministered with alcohol, other CNS depressants, or agents that cause dizziness or vertigo. Patients should not drive, operate machinery, or engage in hazardous activities requiring mental alertness and motor coordination until they know how the medications affect them.

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.