Quetiapine and Suvorexant interaction

• Concomitant use of strong CYP3A4 inhibitors: Reduce quetiapine dose to one‑sixth when coadministered with strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) ( 2.5 , 7.1 , 12.3 )

Quetiapine exposure is increased by the prototype CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, indinavir, ritonavir, nefazodone, etc.) and decreased by the prototype of CYP3A4 inducers (e.g., phenytoin, carbamazepine, rifampin, avasimibe, St.

CYP3A4 inhibitors: Coadministration of ketoconazole, a potent inhibitor of cytochrome CYP3A4, resulted in significant increase in quetiapine exposure.

The dose should be reduced to one‑sixth of the original dose in patients coadministered with a strong CYP3A4 inhibitor [see Dosage and Administration (2.5) and Clinical Pharmacology (12.3) ].

CNS Depressant Effects and Daytime Impairment: Risk of impaired alertness and motor coordination, including impaired driving; risk increases with dose; caution patients taking 20 mg against next-day driving and other activities requiring complete mental alertness ( 5.1 ).

Prescribers should monitor for somnolence and CNS depressant effects, but impairment can occur in the absence of symptoms, and may not be reliably detected by ordinary clinical exam (i.e., less than formal testing of daytime wakefulness and/or psychomotor performance).

Co-administration with other CNS depressants (e.g., benzodiazepines, opioids, tricyclic antidepressants, alcohol) increases the risk of CNS depression.

Dosage adjustments of BELSOMRA and of concomitant CNS depressants may be necessary when administered together because of potentially additive effects.

The risk of next-day impairment, including impaired driving, is increased if BELSOMRA is taken with less than a full night of sleep remaining, if a higher than the recommended dose is taken, if co-administered with other CNS depressants, or if co-administered with other drugs that increase blood levels of BELSOMRA.