On 2014 Feb 26, David Keller commented:

Why is citalopram still being used instead of safer escitalopram?

In the CitAD trial, the use of citalopram predictably led to its known adverse side-effect of QT-interval prolongation, which is a dose-dependent risk factor for toursades de pointes, an often-fatal cardiac arrhythmia. The QT-interval is prolonged further by interactions with numerous common medications, including over-the-counter omeprazole, which the patient may take or be prescribed inadvertently (1). As I have pointed out before (2), (3), the use of escitalopram instead of citalopram reduces the amount of QT-interval prolongation for any given degree of intended therapeutic antidepressant or antianxiety effect. The reason is that the therapeutic benefits of racemic citalopram are caused only by the levorotatory optical isomer (S-citalopram or escitalopram). The dextrorotatory molecule (R-citalopram) causes a roughly equivalent degree of QT-interval prolongation as escitalopram without contributing any known therapeutic effects. The last remaining reason to prescribe citalopram vanished when escitalopram went generic.

Are the cognitive adverse effects of citalopram caused roughly equally by both optical isomers, similar to the cardiac risks? If so, then the significant benefits of citalopram on agitation in Alzheimer's disease could have been achieved with roughly half the degree of cognitive impairment by substituting escitalopram at half the milligram dose instead of citalopram.

(1) Yee Guan Yap, A John Camm. Drug induced QT prolongation and torsades de pointes. Heart. 2003 November; 89(11): 1363–1372.PMCID: PMC1767957

(2) Keller DL. Prescribe escitalopram instead of citalopram. Am J Med. 2013 Jun;126(6):e21. doi: 10.1016/j.amjmed.2012.10.024. No abstract available. PMID: 23684405 [PubMed - indexed for MEDLINE]

(3) Keller DL. Comments and questions regarding the safety of citalopram. Mayo Clin Proc. 2013 Apr;88(4):420. doi: 10.1016/j.mayocp.2013.01.023. No abstract available. PMID: 23541017 [PubMed - indexed for MEDLINE]

On 2014 Feb 26, David Keller commented:

Why is citalopram still being used instead of safer escitalopram?

In the CitAD trial, the use of citalopram predictably led to its known adverse side-effect of QT-interval prolongation, which is a dose-dependent risk factor for toursades de pointes, an often-fatal cardiac arrhythmia. The QT-interval is prolonged further by interactions with numerous common medications, including over-the-counter omeprazole, which the patient may take or be prescribed inadvertently (1). As I have pointed out before (2), (3), the use of escitalopram instead of citalopram reduces the amount of QT-interval prolongation for any given degree of intended therapeutic antidepressant or antianxiety effect. The reason is that the therapeutic benefits of racemic citalopram are caused only by the levorotatory optical isomer (S-citalopram or escitalopram). The dextrorotatory molecule (R-citalopram) causes a roughly equivalent degree of QT-interval prolongation as escitalopram without contributing any known therapeutic effects. The last remaining reason to prescribe citalopram vanished when escitalopram went generic.

Are the cognitive adverse effects of citalopram caused roughly equally by both optical isomers, similar to the cardiac risks? If so, then the significant benefits of citalopram on agitation in Alzheimer's disease could have been achieved with roughly half the degree of cognitive impairment by substituting escitalopram at half the milligram dose instead of citalopram.

(1) Yee Guan Yap, A John Camm. Drug induced QT prolongation and torsades de pointes. Heart. 2003 November; 89(11): 1363–1372.PMCID: PMC1767957

(2) Keller DL. Prescribe escitalopram instead of citalopram. Am J Med. 2013 Jun;126(6):e21. doi: 10.1016/j.amjmed.2012.10.024. No abstract available. PMID: 23684405 [PubMed - indexed for MEDLINE]

(3) Keller DL. Comments and questions regarding the safety of citalopram. Mayo Clin Proc. 2013 Apr;88(4):420. doi: 10.1016/j.mayocp.2013.01.023. No abstract available. PMID: 23541017 [PubMed - indexed for MEDLINE]