Is escitalopram more selective than citalopram?
Escitalopram is the most selective of all SSRIs in clinical use, as expressed by the ratio between noradrenaline (NA) transporter affinity (Ki) and 5-HT transporter affinity, as well as the ratio between NA and 5-HT uptake inhibitory potency (IC50 values), measured in human NA and 5-HT transporters (ref.1).
The affinity of escitalopram for DA transporters is also very weak; consequently, it is also the most selective among SSRIs for 5-HT, cmpared to DA.
Escitalopram can, therefore, be considered to be the most selective serotonin reuptake inhibitor available today (ref.1).
References:
1. Owens et al, 2001