Major
Escitalopram × Haloperidol
Selective serotonin reuptake inhibitors (SSRIs)×First-generation antipsychotics. Butyrophenone derivatives
Mechanism
Additive QT prolongation. Escitalopram prolongs QT dose-dependently (FDA Lexapro caps at 20 mg/day) and haloperidol prolongs QT too. In patients with hypokalaemia, hypomagnesaemia, ischaemic heart disease, or bradycardia, torsades de pointes risk is especially high.
Symptoms
QT prolongation on ECG. Clinically: dizziness, syncope, palpitations. Severe cases progress to polymorphic ventricular tachycardia (torsades de pointes) with risk of ventricular fibrillation and sudden cardiac death. Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Avoid the combination. Alternative antipsychotics with minimal QT effect: olanzapine or aripiprazole. Alternative antidepressants: mirtazapine or agomelatine.