Duloxetine (brand name Cymbalta) is a serotonin-norepinephrine reuptake inhibitor (SNRI) that has FDA approval to treat depression as well as fibromyalgia in adults. As with other antidepressants, it carries a “black box warning” from the FDA that it has the potential to increase suicidal thoughts and behaviors, especially in adolescents. Now, a new, as-yet-unpublished trial of duloxetine for fibromyalgia has presented more evidence of suicidal events in teens treated with this drug.
The trial is reported on at clinicaltrials.gov, where it is shown as completed. However, the trial has, as yet, been unpublished. The trial itself was sponsored by Eli Lilly, the makers of Cymbalta, and the researchers have a nondisclosure agreement with the company—meaning that they cannot publish these results unless Eli Lilly allows them to do so.
The trial data, however, is publicly available. The purpose of the study was to investigate whether duloxetine was efficacious for treating fibromyalgia in adolescents. The study included 184 children, all between the ages of 13 and 17, who had a diagnosis of Juvenile Primary Fibromyalgia Syndrome. The participants were randomly assigned to receive either duloxetine or placebo for 13 weeks (blinded treatment period); at the end of that time, all participants were given duloxetine for an additional 26 weeks (open-label period).
Duloxetine appeared to be successful for reducing fibromyalgia pain, with most measures showing a decrease when compared to placebo. However, due to duloxetine’s potential to increase suicidal thoughts and behaviors (especially in this age group), a look at the reported side effects is warranted.
The data shows that, of those taking duloxetine, six children exhibited suicide-related side-effects. There were two suicide attempts as well as an intentional overdose (the reporting system groups this separately from suicide attempts). One child engaged in self-injurious behaviors and two others exhibited suicidal thoughts that they did not act on. No participants in the placebo group had any kind of suicidal thoughts or behaviors.
Other dangerous side effects encountered by children taking duloxetine included a report of auditory hallucinations, a report of depression, a report of seizure—and two teens who developed appendicitis (compared to none in the placebo group).
In terms of less life-threatening side effects, nausea, vomiting, and headaches were commonly reported. Other side effects reported more commonly in the duloxetine group than in the placebo group included viral gastroenteritis, upper respiratory tract infection, fatigue and dizziness. Over 80% of the children in the initial duloxetine group experienced some kind of side effect, compared with around 60% in the placebo group.
Duloxetine carries FDA approval for treatment of depression, although a 2012 Cochrane reviewsuggested that it should not be a first-line drug for this purpose. That review found that it was no more effective than any other antidepressant, but that it carried more risk of side effects. In fact, according to a 2015 Cochrane review, almost everyone taking duloxetine will experience side effects, usually nausea and vomiting and/or sleep disorders. Duloxetine is also FDA-approved for the treatment of fibromyalgia pain in adults.