E X P E R T O P I N I O N Duloxetine for the treatment of generalized anxiety disorder : a review Ahsan Y Khan Matthew Macaluso Department of Psychiatry and Behavioral Sciences, University of Kansas School of Medicine-Wichita, Wichita, KS, USA Correspondence: Ahsan Y Khan, MD Department of Psychiatry and Behavioral Sciences, University of Kansas School of Medicine-Wichita, 1010 N. Kansas Street,Wichita, KS 67214, USA Email akhan@kumc.edu Abstract: Approximately 16 million people in the United States suffer from anxiety disorders alone, while another 12 million experience both anxiety and at least one other psychiatric condition. Generalized anxiety disorder (GAD) has lifetime prevalence rates between 5% and 6%. Treatment of GAD is aimed primarily at symptom reduction. Duloxetine, a serotonin norepinephrine reuptake inhibitor (SNRI), received Food and Drug Administration (FDA) approval for the treatment of GAD in 2007. This article reviews the pharmacologic proﬁle and seminal clinical trials associated with the FDA indication of duloxetine for GAD. A literature search performed using PubMed with the keywords “duloxetine”, “gad”, “generalized anxiety disorder”, and “venlafaxine XR” yielded 27 articles. We also focused on papers that pooled data from these seminal studies. Data on ﬁle from Eli Lilly were also reviewed, including data from the Eli Lilly website. Based on this search, duloxetine was found to be an FDA-approved treatment option for GAD that has been studied in several double-blind, placebo-controlled clinical trials. This review of duloxetine will help physicians to interpret clinical studies properly and also help them to make an informed decision about which patients are the most appropriate candidates for a trial of duloxetine. Keywords: duloxetine, generalized anxiety disorder, clinical trials, serotonin norepinephrine reuptake inhibitor (SNRI) Introduction Anxiety disorders were classiﬁed as neurotic disorders until the establishment of the DSM-III in 1980. Approximately 16 million people in the United States suffer from anxiety disorders alone, while another 12 million experience both anxiety and at least one other psychiatric disorder.1 Generalized anxiety disorder (GAD) involves excessive worry about everyday life events, on more days than not, for a period of at least 6 months.2 According to DSM-IV-TR, patients must ﬁnd it “difﬁcult to control the worry” and must present with 3 of the following 6 criteria: restlessness or feeling keyed up, being easily fatigued, difﬁculty concentrating or mind going blank, irritability, muscle tension, or sleep disturbance.2 Patients with GAD often present hyper-vigilant, with somatic complaints such as musculoskeletal pain or gastrointestinal disturbance.3 GAD has lifetime prevalence rates between 5% and 6%, and a male to female ratio of 1:2.4 Treatment of GAD is aimed at symptom reduction, often utilizing selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), buspirone, benzodiazepines and/or psychotherapy. In 1991, Butler et al published evidence supporting the use of cognitive behavioral therapy (CBT) in the treatment of GAD.5 Both venlafaxine and duloxetine have been Food and Drug Administration (FDA) approved for the treatment of GAD. Another SNRI, milnacipran, is not yet available in the United States, but is utilized clinically to treat major depressive disorder (MDD) and chronic pain in other parts of the world including Europe.6 Duloxetine, an SNRI, received FDA approval for MDD Neuropsychiatric Disease and Treatment 2009:5 23–31 © 2009 Khan and Macaluso, publisher and licensee Dove Medical Press Ltd.This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited. 23