Major
Haloperidol × Sertraline
First-generation antipsychotics. Butyrophenone derivatives×Selective serotonin reuptake inhibitors (SSRIs)
Mechanism
Sertraline at high doses prolongs QT, additively with haloperidol. Sertraline also weakly blocks CYP2D6, so haloperidol levels may rise.
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Severe cases: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia and hypomagnesaemia.
Management
Avoid the combination with sertraline above 100 mg and parenteral haloperidol. Alternative antipsychotics with minimal QT effect: olanzapine or aripiprazole. Alternative antidepressants: mirtazapine or agomelatine.