Escitalopram is the therapeutically active S-enantiomer of RS-
citalopram, a commonly prescribed SSRI. The R-enantiomer is essentially pharmacologically inactive.
Escitalopram 10 or 20 mg/day produced significantly greater improvements in standard measurements of
antidepressant effect (Montgomery-Asberg Depression Rating Scale [MADRS], Clinical Global Impressions Improvement and Severity scales [CGI-I and CGI-S] and Hamilton Rating Scale for Depression [HAM-D]) in patients with
major depressive disorder (MDD) than placebo in several 8-week, placebo-controlled, randomised, double-blind, multicentre studies. Symptom improvement was rapid, with some parameters improving within 1-2 weeks of starting
escitalopram treatment. In addition,
escitalopram showed earlier and clearer separation from placebo than RS-
citalopram, at one-quarter to half the dosage, in 8-week, placebo-controlled trials; had significantly better efficacy than RS-
citalopram in a subgroup of patients with moderate MDD in a 24-week trial; and produced sustained response and remission significantly faster than
venlafaxine extended release in patients with MDD.
Escitalopram reduced relapse rate compared with placebo and increased the percentage of patients in remission in long-term trials (up to 52 weeks). Consistently significant improvements for all efficacy parameters were also observed in patients with generalised
anxiety disorder, social anxiety disorder and
panic disorder treated with
escitalopram for 8-12 weeks in individual, randomised, placebo-controlled, double-blind investigations. The good tolerability profile of
escitalopram is predictable and similar to that of RS-
citalopram. Such adverse events as
nausea, ejaculatory problems, diarrhoea and
insomnia are expected but, with the exception of ejaculatory problems and
nausea, which is mild and transient, these were generally no more frequent than with placebo in fully published clinical trials. No adverse events not previously seen in acute trials were reported with long-term use.
CONCLUSIONS:
Escitalopram, the S-enantiomer of RS-
citalopram, is a highly selective inhibitor for the
serotonin transporter, ameliorates depressive symptoms in patients with MDD at half the RS-
citalopram dosage, has a rapid onset of symptom improvement and has a predictable tolerability profile of generally mild adverse events. Like RS-
citalopram,
escitalopram is expected to have a low propensity for drug interactions, a potential benefit in the management of patients with comorbidities. In combination, these properties place
escitalopram, like other
SSRIs, as first-line
therapy in patients with MDD.
Escitalopram is indicated for use in patients with
panic disorder in Europe and, should further evidence confirm early findings that
escitalopram reduces anxiety, the
drug may well find an additional role in the management of
anxiety disorders.