Major
Amiodarone × citalopram
Class III antiarrhythmics (Vaughan Williams)×SSRI (selective serotonin reuptake inhibitor)
Mechanism
Dual QT-prolongation risk. Citalopram carries an FDA boxed warning about dose-dependent QT effect (FDA Celexa caps at 40 mg/day); amiodarone is a potent QT-prolonging drug.
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: mirtazapine or agomelatine (minimal QT effect). If citalopram is needed, cap at 20 mg/day; ECG before start and at 2 weeks.
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.