The maximum daily dose of citalopram has been reduced from 60mg to 40mg owing to the risk of dose-dependent QT interval prolongation. In the elderly and in patients with reduced hepatic function, the maximum dose is lowered to 20mg daily.
ECG monitoring revealed a dose-dependent prolongation of the QT interval in healthy patients taking citalopram. Patients with underlying heart conditions and those who are predisposed to hypokaleamia or hypomagnesaemia are particularly at risk of QT interval prolongation.
Cases of ventricular arrhythmia including torsade de pointes have also been identified in citalopram-treated patients.
Other studies have not shown an additional benefit of citalopram at doses higher than 40mg daily in the treatment of depression. Citalopram is now contraindicated in patients with known QT interval prolongation or congenital long QT syndrome.
Patients who are on higher doses will need to be identified, reviewed and doses gradually reduced.
Cases of QT interval prolongation have also been reported with other SSRIs including escitalopram (Cipralex).