Major
citalopram × Dronedarone
SSRI (selective serotonin reuptake inhibitor)×Class III antiarrhythmic
Mechanism
Dronedarone prolongs QT (FDA Multaq carries a boxed warning). Citalopram does so dose-dependently. Additive torsades de pointes risk.
Symptoms
QT prolongation on ECG. Clinically: dizziness, syncope, palpitations. Severe cases progress to polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Avoid the combination. Alternative antidepressants with minimal QT effect: mirtazapine or agomelatine. Alternative antiarrhythmic: a beta-blocker for rate control.