A New Treatment for Fibromyalgia?

Fibromyalgia can be characterized as widespread or multi-site pain that is present for at least three months and not attributed to another disease or condition.¹ Many other non-pain symptoms are present in patients with fibromyalgia, including chronic fatigue, sleep disturbances, neurologic disturbances and disturbances of cognition and mood. Cognitive impairment can present as difficulty concentrating and forgetfulness, as well as disorganized thinking. Other symptoms can include musculoskeletal stiffness and environmental sensitivity, such as sensitivity to bright lights, loud noises, perfumes and cold.

The prevalence of fibromyalgia in the U.S. is estimated to be 2–6.4%, and the condition is more common in women than in men. On physical examination, there is an absence of focal changes, suggestive of arthritis or enthesitis, and widespread tenderness.²

Patient Care

Fibromyalgia is managed with non-pharmacologic and pharmacologic therapies. Non-pharmacologic interventions include patient education about the disease and cognitive therapy, as well as increased activity and exercise routines. The most common medications prescribed for fibromyalgia, mostly off label, are tricyclic antidepressants, such as amitriptyline and related medications (e.g., cyclobenzaprine); serotonin-norepinephrine re-uptake inhibitors, such as duloxetine and milnacipran; and alpha-2 ligands, such as pregabalin and gabapentin.³

Only three medications have previously been approved by the U.S. Food & Drug Administration (FDA) to treat fibromyalgia:

• Pregabalin (Lyrica), which was approved on June 21, 2007;⁴
• Duloxetine (Cymbalta), which was approved on June 13, 2008;⁵ and
• Milnacipran (Savella), which was approved on Jan. 14, 2009.⁶

New Treatment

On Aug. 15, the FDA approved a new drug application for Tonmya (TNX-102 SL) for the treatment of adults with fibromyalgia.⁷ This agent is a rapidly disintegrating sublingual tablet with 2.8 mg of cyclobenzaprine HCl.⁸ The FDA initially approved cyclobenzaprine as a skeletal muscle relaxant on Aug. 26, 1977.⁹ The agent has been widely used off label as a treatment for fibromyalgia and available as a generic medication for many years. The most common adverse reactions are drowsiness, dry mouth, dizziness and fatigue.

Developed by Tonix Pharmaceuticals, TNX-102 SL is designed to provide rapid transmucosal absorption and—due to its bypass of first-pass, hepatic metabolism—reduce the production of norcyclobenzaprine, a long half-life active metabolite.¹⁰ The medication was formulated for optimal delivery and absorption to improve sleep quality, while minimizing the potential residual effects of oral cyclobenzaprine formulations. It is a centrally acting analgesic that helps relieve pain by improving sleep.

The Latest Research

In the phase 3 RESILIENT trial (NCT05273749), patients with fibromyalgia treated with TNX-102 SL had significant reductions in daily pain and tolerated the medication well, with minimal side effects.¹¹