Escitalopram increases intrasynaptic levels of the neurotransmitter serotonin by blocking the reuptake of the neurotransmitter into the presynaptic neuron.
Escitalopram, similarly to other SSRIs (with the exception of fluvoxamine), inhibits CYP2D6 and hence may increase plasma levels of a number of CYP2D6 substrates such as aripiprazole, risperidone, tramadol, codeine, etc.