The mechanism of fibromyalgia, a chronic illness characterized by muscle pain, fatigue, and sleep disturbances, is unknown and medications used to treat it (such as antidepressants, antiepileptics, muscle relaxants, antiinflammatories, sedative hypnotics, pain relievers and nutriceuticals) have had limited success. New research findings indicate that the pain associated with this disease may be due to abnormal sensory processing in the central nervous system.
Recently, researchers from Pacific Rheumatology Associates in Renton, Washington set out to investigate whether the dopamine receptor agonist pramipexole was safe and effective in treating fibromyalgia. Normally used to treat Parkinson's disease, this drug stimulates dopamine (a neurotransmitter) production by binding to dopamine receptor sites and is thought to inhibit sensory nerve-mediated responses. This is the first trial of pramipexole and only the second trial for this type of dopamine receptor agonist for the treatment of fibromyalgia. The findings are published in the August 2005 issue of Arthritis & Rheumatism.
The study was a single-center, double-blind, placebo-controlled trial involving 60 patients with fibromyalgia who were randomly selected in a 2:1 ratio to receive either pramipexole or a placebo every evening for 14 weeks. The dosage for those receiving the drug was increased weekly, starting at 0.25 mg the first week and ending at 4.5 mg for the last three weeks; it was then tapered to 0 mg during week 15. Because fibromyalgia patients often take a variety of medications, participants were allowed to continue these as long as the dosage had been stable for at least 6 weeks prior to the beginning of the study. A total of 49 patients completed the study due to a variety of reasons, the most common of which was violating protocol by starting a new medication during the study period. None withdrew because of side effects.