The following announcement on the FDA approval of Cymbalta for treatment of Generalized Anxiety Disorder (GAD) is important on a number of fronts.
U.S. Regulators Approve Cymbalta(R) for Treatment of Generalised Anxiety Disorder | March 2, 2007 | PRNewswireU.S. Regulators Approve Cymbalta(R) for Treatment of Generalised Anxiety Disorder
March 2, 2007 - 8:22 AM INDIANAPOLIS, February 26/PRNewswire/ --The U.S. Food and Drug Administration (FDA) has approved the antidepressant Cymbalta(R) (duloxetine HCl) for the treatment of generalised anxiety disorder (GAD), Eli Lilly and Company (NYSE: LLY) and Boehringer Ingelheim announced today.
The approval is based on the results of three randomized, double-blind, placebo-controlled studies in which the safety and efficacy of duloxetine in the treatment of GAD was studied in more than 800 non-depressed adults. In all studies, duloxetine significantly improved core anxiety symptoms as measured by the Hamilton Anxiety Scale (HAMA), compared with placebo.(i,ii ,iii) In addition, duloxetine patients reported greater improvement in functional impairment associated with the illness, including improved ability to perform everyday activities at work, home, and in social situations.(iv,v)
First, the studies continue the practice within the FDA of insisting on homogeneous symptoms. Participants in the studies had to have GAD and not depression. While this makes intuitive scientific sense (you exclude other disorders to see if the medication works on the target symptoms of your study, in this case GAD), it does not represent reality. In the real world, we know from epidemiological studies that fully 80% of the population who have any anxiety disorder (including, probably especially GAD) also have concurrent depression or other mental health disorders. This is called comorbidity. Insisting on a homogeneous study population thus excludes most patients who will actually begin taking the drug based upon physician prescription.
Second, it highlights the notion that most mental disorders are defined by high emotional arousal. I call this in my professional book (DBT in Private Practice) the "single factor" theory. Most major mental disorders (mood disorders, anxiety disorders, impulse control disorders, personality disorders, etc.) respond to the SSRI and SNRI class of medications. Their responsiveness to a variety of disorders suggests that our current diagnostic system (that pretends that disorders are separate and discrete phenomena (like the difference between an infection versus a broken bone) simply does not apply in mental health.
Third, it highlights the prevalence and disability that occurs with GAD. It is a disorder that severely impacts individuals ability to lead lives worth living.
