Escitalopram (Cipralex®), a new highly selective inhibitor of serotonin reuptake, is the activeS-enantiomer ofRS-citalopram. It is effective in the treatment of patients with major depressive disorder (MDD) and may have a faster onset of therapeutic effect than citalopram. It has also been shown to lead to improvements in measures of quality of life (QOL). Escitalopram is generally well tolerated, with nausea being the most common adverse event associated with its use.Modelled pharmacoeconomic analyses found escitalopram to have a cost-effectiveness and cost-utility advantage over other SSRIs, including generic citalopram and fluoxetine and branded sertraline, and also over the serotonin-noradrenaline reuptake inhibitor (SNRI) venlafaxine extended-release (XR). These studies used a decision-analytic approach with a 6-month time horizon and were performed in Western Europe (year of  costing  2000  or  2001). Cost-effectiveness ratios for escitalopram, in terms of cost per successfully treated patient over 6 months, ranged from euro871 to euro2598 in different countries, based on direct costs and remission rates, and were consistently lower (i.e. more favourable) than the ratios for comparators (euro970–euro3472). Outcomes similarly favoured escitalopram when indirect costs (represented by those associated with sick leave and loss of productivity) were included. The results of comparisons with citalopram, fluoxetine and sertraline were not markedly affected by changes to assumptions in sensitivity analyses, although comparisons with venlafaxine XR were sensitive to changes in the remission rate.The mean number of quality-adjusted life years gained during the 6-month period was similar for all drugs evaluated, but direct costs were lower with escitalopram, leading to lower cost-utility ratios than for comparators. Incremental analyses performed in two of the studies confirmed the cost-effectiveness and cost-utility advantage of escitalopram.A prospective, 8-week comparative pharmacoeconomic analysis found that escitalopram achieved similar efficacy to venlafaxine XR, but was associated with 40% lower direct costs (euro85 vs euro142 per patient over 8 weeks; 2001 costs), although this difference did not reach statistical significance.In both the modelled and prospective analyses, the differences in overall direct costs were mainly due to lower secondary care costs (in particular those related to hospitalisation) with escitalopram. In the prospective analysis, escitalopram had lower estimated drug acquisition costs than venlafaxine XR.ConclusionEscitalopram, theS-enantiomer ofRS-citalopram and a highly selective inhibitor of serotonin reuptake, is an effective antidepressant in patients with MDD, has a favourable tolerability profile, and, on the basis of available data, appears to have a rapid onset of therapeutic effect. Modelled pharmacoeconomic analyses from Western Europe suggest that it may be a cost-effective alternative to generic citalopram, generic fluoxetine and sertraline. Although the available data are less conclusive in comparison with venlafaxine XR, escitalopram is at least as cost effective as the SNRI based on a prospective study, and potentially more cost effective based on modelled analyses. Overall, clinical and pharmacoeconomic data support the use of escitalopram as first-line therapy in patients with MDD.