Escitalopram is a new patent of the widely sold citalopram. The main idea is a seperation of the two isomer molecules of the drug. Only the S-active enantiomer contributes to the antidepressant effect. By removing the inactive R-isomer the pharmacompany promises a stronger effect, faster acting and lower side effects. But there is limited knowledge about the true reasons to promote this drug. One of the main reasons will be the exclusise patent right of these drugs.