10 Off-label Uses of Antidepressants

Managing Chronic Pain of Fibromyalgia
Fibromyalgia is a musculoskeletal syndrome; it comes with a variety of symptoms that often overlap with other conditions, making diagnosis difficult. ©iStock/Thinkstock

A patient experiences chronic pain, fatigue, changes in memory and changes in mood; what's the diagnosis? Those are the symptoms of fibromyalgia, a musculoskeletal pain syndrome affecting an estimated 5 million adults in the U.S. The majority of patients are female [source: NIAMS]. It's difficult to diagnose fibromyalgia, as its characteristics and symptoms are common among various disorders and diseases.

Its cause is unknown; some theories suggest hormonal triggers, while others point to associations between the syndrome and viral infections. Some studies suggest a link between sleep disorders and fibromyalgia, while others point to a possible link with depression. Or, there could be a link between genetic markers called human leukocyte antigens and fibromyalgia. And still more studies suggest biochemical changes in the muscles and the central nervous system may play a role in its onset.

Just as there's no definitively known cause for fibromyalgia, there's also no cure, but the symptoms can be managed. Analgesics (painkillers) and nonsteroidal anti-inflammatory drugs (NSAIDs) are essential to chronic pain management. Certain anti-seizure medications are also considered effective fibromyalgia treatments. And so are antidepressants, as it turns out.

Antidepressants increase the levels of two neurotransmitters — serotonin and norepinephrine — in the brain, changing the way the brain processes pain. Serotonin‐norepinephrine reuptake inhibitors (SNRIs), selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) are among medications used off-label to manage chronic pain, and have been used — also off-label — for years to treat fibromyalgia-associated pain and its concomitant symptoms, such as depression and fatigue [source: OSU]. In 2009 the FDA approved the first antidepressant to treat fibromyalgia, the SNRI milnacipran (Savella); and in 2010 another SNRI, duloxetine (Cymbalta) was approved to treat not only depression but fibromyalgia as well.