About Escitalopram Selective Serotonin Reuptake Inhibitor (SSRI), Antidepressant. Mechanism of Action of Escitalopram Escitalopram is the S enantiomer of racemic Citalopram. It is 100 times more potent than R-enantiomer. Escitalopram blocks the re-uptake of neurotransmitter Serotonin from the synapse to the presynaptic nerve terminal in the CNS. This potentiates the action of Serotonin (5HT) and it is useful in the treatment of depression. Indications for Escitalopram Depression. Typical Dosage for Escitalopram Adult: Initial dose: 10 mg / day, dose can be increased to 20 mg / day if sufficient response does not occur after a minimum of 1 week.