The use of escitalopram beyond major depression : pharmacological aspects, efficacy and tolerability in anxiety disorders

Escitalopram, the active (S)-enantiomer of citalopram, has been approved in many countries throughout the world for the treatment of depression and anxiety disorders. It is more potent and selective than citalopram in inhibiting serotonin re-uptake in the CNS, and less potent than various other selective serotonin re-uptake inhibitors in relation to other transporter proteins and receptors: in particular, it is six times less potent than citalopram in binding to the histamine H1 and muscarinic receptors. Escitalopram has favourable pharmacokinetics: it is rapidly absorbed, has a bioavailability of 80% and is not affected by food intake. It has little potential for drug interactions: it has low protein binding and, as it is metabolised by three CYP isozymes, any impairment in the activity of one is unlikely to have a significant effect on metabolic clearance. Caution is necessary only when it is coadministered with drugs metabolised by CYP2D6, such as metoprolol, or administered to the elderly or patients with severe hepatic or renal impairment. The multiple-dose pharmacokinetics of oral escitalopram are proportional at a range of doses including its therapeutic doses. Escitalopram is approved for the treatment of a number of anxiety disorders. It seems to be well tolerated and induces few or no discontinuation symptoms, and may be considered a first-line agent for the pharmacotherapy of obsessive-compulsive disorder, generalised anxiety disorder, panic disorder and social phobia. Further studies are needed to define its activity in impulse control disorders.