Patients with fibromyalgia treated with a synthetic form of marijuana, nabilone, showed significant reductions in pain and anxiety in a first-of-its-kind study, published in The Journal of Pain.
Fibromyalgia syndrome has no cure, is difficult to diagnose, and effective pain management strategies are a must to help patients cope with the disease. An estimated 12 million Americans have fibromyalgia, which is characterized by widespread muscle and joint pain and myriad other symptoms. The condition is far more prevalent in women and the incidence increases with age, reaching 7 percent among women 65 years and older.
Forty subjects were selected for the nabilone trial, conducted by researchers at the University of Manitoba Rehabilitation Hospital. They were divided into nabilone and placebo groups and were treated for four weeks. The authors noted this was the first randomized, controlled-access trial to evaluate nabilone for pain reduction and quality-of-life improvement in fibromyalgia patients. Nabilone is one of two oral marijuana-based compounds, known as cannabinoids, available in Canada and is approved for treatment of nausea and vomiting during chemotherapy.
Results of the Manitoba study showed the nabilone group had significant reductions in pain and anxiety, measured by comparisons with baseline scores on the visual analogue scale for pain, the Fibromyalgia Impact Questionnaire (FIQ) and the FIQ anxiety score. From the data, the study concluded nabilone has significant benefits for pain relief and functional improvement in fibromyalgia patients. Although the improvement was significant, none of the nabilone-treated subjects had complete relief of their fibromyalgia symptoms.
The drug was well tolerated by treated patients, which the authors characterized as reassuring since fibromyalgia patients are sensitive to most medications and have difficulty tolerating side effects. The downside, however, is cost. In Canada, nabilone would cost about $4,000 for a year’s supply.
The authors believe their findings warrant consideration of nabilone as an adjunct to current medical management of fibromyalgia.
Researchers at the University of Florida applied heat stimuli to the hands of healthy controls and fibromyalgia patients. In contrast to normal controls, fibromyalgia patients experienced a great amount of cumulative pain from these stimulations, indicating abnormalities in spinal cord pain processing.
Furthermore, the fibromyalgia patients experienced residual pain when the stimuli were applied at intervals at which the healthy controls were not affected. Normally, pain sensations quickly subside after a single heat stimulus, but will accumulate with repetitions if they occur frequently enough. This “pain memory” appears to linger for an abnormally long period of time in fibromyalgia patients.
The researchers also found that the residual pain experienced by fibromyalgia patients was widespread and not limited to a single area of the body.
“Because the effect of the first experimental stimulus does not rapidly decay in fibromyalgia patients, the effect of subsequent stimuli adds to the first, and so on, resulting in ever increasing pain sensations,” said lead investigator Roland Staud, MD. “Our findings provide evidence for abnormal central nervous system mechanism of pain in fibromyalgia patients and have significant implications for future therapies, which need to target these abnormal central pain mechanisms.
Sources: Sciencedaily.com, American Pain Society
