Major
Amitriptyline × citalopram
Tricyclic antidepressants (TCA)×SSRI (selective serotonin reuptake inhibitor)
Mechanism
Both drugs prolong QT and are serotonergic. Citalopram weakly blocks CYP2D6, a partial amitriptyline route, so amitriptyline levels rise modestly.
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 if citalopram fails: mirtazapine or agomelatine. For neuropathic pain, replace amitriptyline with gabapentin or pregabalin.
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.