Drug interactions between aspirin/butalbital/caffeine/codeine and Seroquel

MONITOR: Central nervous system- and/or respiratory-depressant effects may be additively or synergistically increased in patients taking multiple drugs that cause these effects, especially in elderly or debilitated patients.

MANAGEMENT: During concomitant use of these drugs, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

MONITOR: Coadministration with drugs that are inducers of CYP450 3A4 may decrease the plasma concentrations of quetiapine, which is primarily metabolized by the isoenzyme. In ten subjects with various affective disorders, the 3A4 inducer phenytoin (100 mg orally three times a day) decreased the mean steady-state peak plasma concentration (Cmax), trough plasma concentration (Cmin) and area under the concentration-time curve (AUC) of quetiapine (250 mg orally three times a day) by 66%, 89% and 80%, respectively. The mean oral clearance increased by 5.5-fold. The interaction has not been studied with other 3A4 inducers. However, the possibility of a diminished therapeutic response to quetiapine should be considered in patients receiving concomitant therapy with these agents.

MANAGEMENT: Pharmacologic response to quetiapine should be monitored more closely whenever a CYP450 3A4 inducer is added to or withdrawn from therapy, and the quetiapine dosage adjusted as necessary. Patients should be advised to notify their physician if they experience a worsening of their symptoms or an increase in side effects.