Escitalopram: superior to citalopram or a chiral chimera?

Escitalopram is the active isomer of the antidepressant citalopram. In theory single-isomer drugs may be superior but few have been found to have clinically significant advantages. The manufacturer claims that escitalopram has more efficacy and a faster onset of effect than citalopram. The purpose of this study was to assess how far these claims are justified.

Relevant trial reports were requested from H. Lundbeck A/S and the Swedish drug regulatory authority. The trials consisted of a pooled analysis of 1,321 patients from one unpublished, one partly published and one published eight-week trial, as well as a 24-week trial with 357 patients published as a poster. The studies compared escitalopram with placebo and/or citalopram in outpatients aged or=18 years who met specified criteria for depression. The trials' quality was assessed with Moncrieff et al.'s quality assessment instrument and the results compared with the claims from the advertisements.

The advertising claims are not justified because they are based on secondary outcomes, non-intention-to-treat analyses and arbitrarily defined subgroups. The subgroup results are inconsistent. Methodological flaws in the trials could account for the differences found. Even if the differences claimed were real they appear too small to justify higher prices.

On the evidence available to us the manufacturer's claims of superiority for escitalopram over citalopram are unwarranted. The Swedish and Danish drug regulatory authorities reached similar conclusions. This highlights the need for wider dissemination of national authorities' statements to other countries affected by the European Union's mutual recognition procedure.