Letters to the Editor
Inside the isomers: the tale of chiral switches
- Debbie Pelser, Andrew Somogyi
- Aust Prescr 2004;27:109-13
- 1 October 2004
- DOI: 10.18773/austprescr.2004.090
Editor, – Reference is made to the article 'Inside the isomers: the tale of chiral switches' (Aust Prescr 2004;27:109-13). In this article it is asserted that &aos;in overdose, there is a concern about the potential for sudden death, possibly related to QT prolongation due to a secondary metabolite formed from (R)-citalopram. (S)-citalopram (escitalopram) was therefore developed with the aim of a better harm: benefit ratio compared to (R)-citalopram'.
Significantly, the authors of this article have not referenced any of the statements in this paragraph. I would like to advise that the statement regarding the propensity of a metabolite of the (R)-enantiomer of citalopram to cause sudden death as a result of QT prolongation is completely unfounded.
A survey has investigated the effects of citalopram, at therapeutic doses, on ECG parameters.1 The authors concluded that citalopram has no significant effects on PQ, QRS or QTc intervals, during short-or long-term treatment. Nor were there any deaths or clinically significant arrhythmias reported among all pure citalopram intoxications (n=108 with doses up to 5.2 g) over a two-year period in Sweden.2
Since there is absolutely no basis to the assertion that a metabolite of (R)-citalopram is associated with sudden death as a result of QT prolongation, the reason given for the development of (S)-citalopram is also purely speculative and quite simply, untrue.
Medical Department Manager
Baulkham Hills, NSW
Associate Professor Andrew Somogyi, one of the authors of the article, comments:
There is evidence that the didesmethyl metabolite of (R)-citalopram prolongs the QT interval in animals and therefore might contribute to those rare instances of cardiac arrhythmia after very high doses of citalopram in a suicidal setting.3456
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Medical Department Manager, Lundbeck Australia Baulkham Hills, NSW
Department of Clinical and Experimental Pharmacology, University of Adelaide, Adelaide