Onset of Citalopram Cardiotoxicity Can Be Delayed
November 2, 2009, 7:09 am
CITALOPRAM OVERDOSE: LATE PRESENTATION OF TORSADES DE POINTES (TdP) WITH CARDIAC ARREST. Tarabar AF et al. J Med Toxicol 2008;4:101.
Abstract
Overdose of citalopram (Celexa) — a selective serotonin reuptake inhibitor antidepressant — can produce life-threatening cardiotoxicity. Manifestations include prolonged QTc interval and torsades de pointes. Because these effects are most likely related to a metabolite (didesmethylcitalopram), onset of significant toxicity can be delayed beyond 6 hours. This case report describes a 36-year-old woman who developed transient TdP with syncope 32 hours after overdosing on 1000 mg of citalopram. The authors point out that although in this case — as with others in the literature — the time of ingestion may be uncertain, the literature clearly indicates that in citalopram overdose cardiac dysrhythmias may be delayed, and that patients should be monitored beyond that commonly used empiric time period of 6 hours. Oddly, they don’t comment on the patient’s markedly abnormal lab values, which indicate at minimum a combined metabolic acidosis and metabolic alkalosis, if not a triple disorder.
precordialthump Says:
Hi Leon,
I would hope that if the patient had presented earlier some degree of QT prolongation would have been detected. The strategy used in my neck of the woods is to monitor an asymptomatic patient for 13 hours post-ingestion of 1000mg (or more) citalopram (8 hours if 600 to 1000mg). Cardiac monitoring is discontinued if QTc <450 ms and the patient remains asymptomatic at this time.
For those who might be interested, the Western Australia Poisons Information Center approach to citalopram OD is detailed at http://lifeinthefastlane.com/2009/09/toxicology-conundrum-017/
Cheers,
Chris
November 7th, 2009