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 (K_i) 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, compared  to DA.

Escitalopram is therefore considered the most selective serotonin reuptake inhibitor available today (ref.1).

References:

1. Owens et al, 2001