Major
Escitalopram × Quetiapine
Selective serotonin reuptake inhibitors (SSRIs)×Atypical antipsychotics
Mechanism
Additive QT prolongation at high quetiapine doses. Escitalopram prolongs QT dose-dependently (FDA caps at 20 mg/day).
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Severe cases: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia and hypomagnesaemia.
Management
The combination is acceptable at low doses: escitalopram ≤10 mg, quetiapine ≤300 mg/day. ECG before start and at 2 weeks; maintain potassium and magnesium. Alternative antipsychotics: olanzapine or aripiprazole.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.