Moderate
Probable
Description
Fluoxetine inhibits CYP2D6 and CYP3A4, increasing quetiapine plasma concentrations and potentially enhancing both therapeutic and adverse effects.
Mechanism
Fluoxetine is a potent CYP2D6 inhibitor and moderate CYP3A4 inhibitor, reducing quetiapine clearance; combined serotonergic tone also modestly increases.
Clinical Significance
Quetiapine levels may rise by 25–75%; increased sedation, metabolic effects, and QTc prolongation have been observed in clinical practice.
Management
Reduce quetiapine dose when adding fluoxetine; monitor for sedation, metabolic changes, and QT prolongation.