obsessive-compulsive spectrum (Hollander et al 2005). In an open-label trial followed by double-blind discontinuation of pathological gambling with anxiety, escitalopram appeared effective (Grant and Potenza 2006). Kirkcaldy et al (2004) reported a case of obsessive-compulsive disorder charac- terized by compulsive vomiting that appeared to respond favorably to escitalopram. Stein et al (2006) conducted the only reported random- ized, double-blind, placebo-controlled trial of escitalopram in OCD, a study that also included the active comparison drug paroxetine. After randomization to ﬁxed doses of escitalo- pram 10 mg/day (n = 113), escitalopram 20 mg/day (n = 114), paroxetine 40 mg/day (n = 117), or placebo (n = 114) for 24 weeks, no signiﬁcant differences in drop-out rates were found between the four groups, although fewer people dropped out of the two escitalopram groups compared with those dropping out of the placebo and paroxetine groups. In terms of efﬁcacy, at 12 weeks, the escitalopram 20 mg/day group and paroxetine groups were superior to placebo, and the escitalopram 10 mg/day group was superior to placebo, albeit with a p value of only 0.052. Compared with placebo, week 12 effect sizes were 0.43 and 0.33 for escitalopram 20 mg/day and paroxetine, respectively. By week 24, both escitalopram groups and the paroxetine group were signiﬁ- cantly superior to placebo in terms of treatment response rates. An analysis of remission, deﬁned as a score on the Yale-Brown Obsessive-Compulsive Scale of less than or equal to 10, showed that only the escitalopram 20 mg group was reliably better than placebo in direct comparison to paroxetine 40 mg, Comparing relapse rates in a large, multi-center study in OCD patients who had responded to 16 weeks of open- label treatment with escitalopram followed by randomized, double-blind treatment with either escitalopram (ﬁxed dose of 10 or 20 mg) or placebo for up to an additional 24 weeks, Fineberg et al (2007) found that escitalopram doses at 10 and 20 mg daily were superior to placebo in preventing relapse. Drop-out rates not related to relapse were similar between the escitalopram and placebo groups. At the end of the open-label part of the study, the response rate (deﬁned by a decrease in the Yale-Brown Obsessive-Compulsive Scale of greater than or equal to 25%) was 74%. Escitalopram safety and tolerability Both short- and long-term outcome are important when evaluating a drug for OCD (Starcevic 2005; Fineberg et al 2007). As such, drug tolerability requires careful consid- eration when evaluating a drug’s role in the treatment of a Neuropsychiatric Disease and Treatment 2007:3(4) Escitalopram for OCD disorder, particularly a chronic disorder such as OCD that often entails long-term treatment. One method of assessing tolerability is to evaluate discontinuation rates due to adverse effects in clinical trials. On this count, discontinuation from escitalopram in some trials tends to be approximately the same as discontinuation rates from placebo (Burke 2002; Fineberg et al 2007). Nonetheless, escitalopram is associated with several adverse effects that potentially can decrease a patient’s quality of life, including dry mouth, insomnia, dif- ﬁculty with ejaculation, nausea, diarrhea, drowsiness (Burke 2002), yawning (Lader et al 2004), fatigue, headache, dizzi- ness, and increased sweating (Montgomery et al 2005). Montgomery et al (2005) found more adverse effects early in their study of escitalopram for generalized social anxiety disorder than later in the study, implying the pos- sibility that tolerance may occur to escitalopram’s adverse effects. Furthermore, when these authors excluded adverse- effect data from the ﬁrst two weeks of their study, they found that adverse effects were similar overall in the escitalopram and placebo groups. Analyzing data for escitalopram tolerability in general- ized anxiety disorder over six months of treatment (Davidson et al 2004), Baldwin and Nair (2005) found that the most commonly reported adverse effects were headache (25.5%), ejaculation disorder (16%), upper respiratory tract infection (15.4%), nausea (15.2%), and insomnia (14.8%). Baldwin and Nair (2005) concluded that in generalized anxiety disorder, escitalopram was better tolerated overall than par- oxetine. Finally, withdrawal from escitalopram appears to be less severe than withdrawal from paroxetine (Montgomery et al 2005). Conclusion – role of escitalopram in OCD Based on currently available ﬁndings, few studies have evaluated the use of escitalopram in OCD and only one placebo-controlled, randomized study was conducted, limit- ing the conclusions that can be drawn about the efﬁcacy of escitalopram in OCD. Several factors, however, suggest that escitalopram may have considerable clinical potential in the treatment of adult OCD. First, it is an SSRI, like other drugs that are considered to be ﬁrst-line drug treatments for OCD (Eddy et al 2004). Second, escitalopram may possess unique advantages compared with other SSRIs in that it consists of not a racemic mixture but rather only the S isomer, a preparation that may target the organization of the nervous system more speciﬁcally than a racemic mixture. Third, escitalopram is the most selective of the SSRIs (Sanchez 459