Fibromyalgia generally affects adult women. However, juvenile fibromyalgia (JFM) is a disorder that affects up to 6% of children and adolescent patients. More girls than boys are affected by JFM, but the disease is all-around underdiagnosed and undertreated. There exist no approved medications for JFM. A laboratory from the Women’s Health Research Program at the University of Cincinnati College of Medicine, in collaboration with the Fatigue Consultation Clinic and the Forest Research Institute, conducted two clinic trials investigating a possible new treatment for JFM. The team found that milnacipran may benefit patients with JFM, but future investigations are necessary to develop the therapeutic agent for regular clinical use.
“The open-label findings provide preliminary evidence that milnacipran may improve symptoms of JFM, with a safety and tolerability profile that is consistent with the experience in adult fibromyalgia patients,” wrote the authors in their study, “Preliminary Experience Using Milnacipran in Patients With Juvenile Fibromyalgi: Lessons From a Clinical Trial Program.” The researchers cannot be definitive with their conclusions about safety and efficacy, as both clinical trials were terminated due to low enrollment.
“Safety and Efficacy of Milnacipran in Pediatric Patients With Primary Fibromyalgia (MyFi)” was a Phase 2, randomized placebo-controlled trial that evaluated the safety, tolerability, efficacy, and pharmacokinetics of minacipran in 13- to 17-year-old patients with JFM. Only 20 patients were randomized into the treatment groups, making statistical analyses irrelevant. “Long-Term Safety and Efficacy Study of Milnacipran in Pediatric Patients With Primary Fibromyalgia (MyFi)” was designed to treat patients open-label with milnacipran for one year to determine the long-term effects. This trial enrolled 116 patients for the initial eight-week open-label period, and 57 patients continued with the open-label extension.
The experimental group was given a maximum tolerated dose (50, 75, or 100 mg) in tablet form each day and monitored for adverse events. To test the efficacy of milnacipran, doctors evaluated the patients at seven clinical visits during the eight-week period and twice during the extension period. Time to loss of therapeutic response, patient global impression of severity, and suicidal behaviors were used to determine if the patients were being helped or harmed by milnacipran.
“During both open-label periods, there were mean improvements in pain severity, patient global impression of severity, pediatric quality of life inventory, and multidimensional anxiety scale for children scores,” wrote the authors. “No unexpected safety issues were detected.” Since there appears to be a benefit of treatment, it will be interesting to look at milnacipran in the future, but it may be difficult to obtain fully-enrolled trials due to the rarity of JFM patients.