The FDA has clarified dosing and warning recommendations for the antidepressant Celexa (citalopram HBr; Forest). In August 2011, the FDA notified healthcare professionals and patients that citalopram should no longer be used at doses >40mg/day because it could cause arrhythmias (eg, QT prolongation and Torsades de Pointes). The drug label has been changed to describe the particular caution that needs to be taken for patients that are at risk.

The revised recommendations state that citalopram is not recommended for use at doses >40mg/day because such doses cause too large of an effect on the QT interval and confer no additional benefit. Additionally, it is not recommended for use in patients with congenital long QT syndrome, bradycardia, hypokalemia, or hypomagnesemia, recent acute myocardial infarction, uncompensated heart failure, and in those who are taking other drugs that prolong the QT interval. The maximum recommended dose of citalopram is 20mg/day for patients with hepatic impairment, patients who are >60 years, CYP 2C19 poor metabolizers, or patients who are taking concomitant Tagamet (cimetidine; GlaxoSmithKline) or another CYP2C19 inhibitor, because these factors can increase the risk of QT interval prolongation and Torsade de Pointes.

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