Major
Established
Description
Escitalopram and quetiapine both prolong the QT interval; concurrent use carries a substantial risk of torsades de pointes and sudden cardiac death.
Mechanism
Both escitalopram and quetiapine block hERG potassium channels in a dose-dependent manner; additive QTc prolongation and increased arrhythmia risk result.
Clinical Significance
QTc prolongation is dose-dependent for both drugs; the FDA has issued safety communications for escitalopram QT effects specifically.
Management
Avoid high doses of either drug when combined; obtain baseline ECG, monitor QTc, and correct electrolytes; consider alternative antipsychotic with lower QT liability.