Escitalopram--translating Molecular Properties into Clinical Benefit: Reviewing the Evidence in Major Depression

The majority of currently marketed drugs contain a mixture of enantiomers; however, recent evidence suggests that individual enantiomers can have pharmacological properties that differ importantly from enantiomer mixtures. Escitalopram, the S-enantiomer of citalopram, displays markedly different pharmacological activity to the R-enantiomer. This review aims to evaluate whether these differences confer any significant clinical advantage for escitalopram over either citalopram or other frequently used antidepressants. Searches were conducted using PubMed and EMBASE (up to January 2009). Abstracts of the retrieved studies were reviewed independently by both authors for inclusion. Only those studies relating to depression or major depressive disorder were included. The search identified over 250 citations, of which 21 studies and 18 pooled or meta-analyses studies were deemed suitable for inclusion. These studies reveal that escitalopram has some efficacy advantage over citalopram and paroxetine, but no consistent advantage over other selective serotonin reuptake inhibitors. Escitalopram has at least comparable efficacy to available serotonin-norepinephrine reuptake inhibitors, venlafaxine XR and duloxetine, and may offer some tolerability advantages over these agents. This review suggests that the mechanistic advantages of escitalopram over citalopram translate into clinical efficacy advantages. Escitalopram may have a favourable benefit-risk ratio compared with citalopram and possibly with several other antidepressant agents.