Published: 2 September 2015

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Reminder: Citalopram and QT Prolongation

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Prescriber Update 36(3): 43
September 2015

Key Messages

  • The maximum dose of citalopram for elderly patients, patients with hepatic impairment, and patients who are CYP2C19 poor metabolisers, or who are taking CYP2C19 inhibitors is 20 mg daily due to increased risk of QT prolongation.
  • The maximum dose for other patients is 40 mg daily.
  • Patients should be screened for risk factors for QT prolongation before starting treatment with citalopram.
  • Citalopram should be stopped and specialist advice sought in patients who have significant QTc prolongation (QTc > 500 ms or an increase of > 60 ms) unless there are compelling reasons to continue.
  • Patients should be advised to contact a healthcare professional immediately if they experience signs and symptoms of an abnormal heart rate or rhythm while taking citalopram.


The Centre for Adverse Reactions Monitoring (CARM) has received a report of a 63-year-old female who was taking 40 mg of citalopram daily. The patient experienced a ventricular tachycardia leading to cardiac arrest and was found to have a prolonged QT interval.

The patient was in end stage renal failure. Although citalopram is eliminated more slowly in patients with mild to moderate renal impairment a dose adjustment is not necessary. However, no information is available on treatment of patients with severely reduced renal function and prescribers are advised to use caution1.

Healthcare professionals are reminded that citalopram is associated with a dose dependent increase in the risk of QT prolongation2. The maximum dose of citalopram is 40 mg a day due to the increased risk of QT prolongation with no additional benefit1.

In elderly patients, patients with reduced hepatic function, patients who are CYP2C19 poor metabolisers, and patients taking CYPC19 inhibitors (eg, cimetidine and omeprazole), the maximum dose should not exceed 20 mg a day because these factors lead to increased blood levels of citalopram1.

QT prolongation is a measure of delayed ventricular repolarisation, which can cause Torsades de Pointes, ventricular tachycardia, and sudden death. A corrected QT interval (QTc) of greater than 500 ms or an increase in the QTc of greater than 60 ms is considered to confer a high risk of Torsades de Pointes3.

Citalopram should be discontinued and specialist advice sought in patients who are found to have persistent QTc greater than 500 ms or an increase of greater than 60 ms unless there are compelling reasons to continue.

QT prolongation risk factors include female gender, increasing age, genetic predisposition, structural heart disease, hypokalaemia, hypomagnesaemia, and interactions with other medicines3.

Prescribers should advise patients to contact a healthcare professional immediately if they experience signs and symptoms of an abnormal heart rate or rhythm while taking citalopram.

Further information on QT prolongation can be found in the Prescriber Update article ‘Drug-induced QT prolongation and Torsades de Pointes — the facts’3.

References
  1. Actavis New Zealand Limited. 2014. Arrow - Citalopram Data Sheet. 24 April 2014. URL: www.medsafe.govt.nz/profs/datasheet/a/ArrowCitalopramtab.pdf (accessed 28 July 2015).
  2. Food and Drug Administration. 2012. Revised recommendations for Celexa (citalopram hydrobromide) related to a potential risk of abnormal heart rhythms with high doses. FDA Drug Safety Communication 28 March 2012. URL:www.fda.gov/Drugs/DrugSafety/ucm297391.htm (accessed 28 July 2015).
  3. Medsafe. 2010. Drug-induced QT prolongation and Torsades de Pointes — the facts. Prescriber Update 31(4): 27–29. URL:www.medsafe.govt.nz/profs/PUArticles/DrugInducedQTProlongation.htm (accessed 28 July 2015).
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