Fibromyalgia syndrome (FMS) is a non-articular rheumatic disease. FMS is a complex, chronic, painful condition that can be characterized by a variety of non-specific symptoms including palpable tender points, chronic, poorly defined, diffuse musculoskeletal pain, morning stiffness, fatigue, weakness and sleep disturbance.

About 2-5% of the general population is considered to have fibromyalgia, of whom 85% are women. Direct medical costs associated with FMS, are estimated to be approximately USD 9- 13 billion per year in the US.

Current treatment is based on a combination of exercise programs and physical therapy, relaxation techniques and patient education, and pharmacotherapy. Despite the high prevalence and severity of FMS treatment is predominantly by off label use of drugs including anti-depressants, anti-seizure drugs and medications approved for neuropathic pain. Therapies are still prescribed on a trial and error basis and patients will often receive a variety of medications before getting a therapeutic response.

With the launch of new drugs, which are specifically approved for treatment of FMS and which include Duloxetine and Pregabalin new treatment options are reaching the market and public disease awareness is increasing. Use of such drugs in FMS represents commercial opportunities for efficacious compounds in an emerging market with projected sales in excess of USD 200 Mio worldwide.

However, despite these recent advances a significant percentage of patients will remain treatment refractory due to lack of efficacy or side effects. The etiology of FMS is unknown and multi-factorial. Abnormalities of pain processing appear to play an important role for fibromylagia pain, particularly those related to deep tissue impulse input, central sensitization, and mood abnormalities. Significant abnormalities in the metabolism of neurotransmitters in the central and peripheral nervous systems have been uncovered in recent years and provide new molecular targets for therapeutic intervention.