Fibromyalgia And Alternative Treatments

[EDDIEKIRK]

Cannabinoids and Pain







Although no cannabinoids are currently FDA-approved as analgesics, there is ongoing research on their efficacy. A recent study on use of nabilone in patients with fibromyalgia found a significant reduction in pain compared with placebo.² Patients receiving nabilone reported significantly more adverse effects, including drowsiness, but none of these were considered serious. Nabilone is also being studied in the United States for its efficacy in neuropathic pain associated with cancer chemotherapy.



Sativex, a combination of THC and cannabidol (the latter agent is not psychoactive), is in phase 3 trials in the United States for relief of cancer-related pain. Sativex is approved in Canada for the treatment of neuropathic pain associated with multiple sclerosis and as an adjunctive analgesic for moderate to severe pain in patients with cancer who have pain despite strong opioid therapy. Unlike dronabinol and nabilone, Sativex is administered in an oral spray.



Both sides of the debate The use of marijuana itself as a medicine is controversial. Several states have approved medical marijuana use and others have considered approving it. However, so far, the federal government has remained unalterably opposed to its legalization, and it remains a Drug Enforcement Administration Schedule I drug.



The debate over whether marijuana should be available for the management of pain has centered on several issues. Those who support its use point out that there is much anecdotal evidence and some formal research supporting marijuana's beneficial effects. Regarding concerns about its potential for abuse, proponents counter that opioids, which also can be abused, are legal.



In addition to concerns about efficacy, opponents of the legalization of medical marijuana cite the lack of standardization of the ingredients or potency of the marijuana available in the states where its use has been legalized. Furthermore, there is limited information on optimal dosing. In Canada, where medical marijuana is legal, there is controversy over whether the government's recommendation that the dosage be limited to 1 to 3 g daily has a scientific basis.³



Smoking marijuana also carries the potential for lung damage. In addition, as previously mentioned, there is the debate over whether medical use of marijuana is simply an attempt to subvert the current laws on recreational use. There have been many reports that where medical marijuana use is allowed, some physicians who are recommending it and some providers of it are lax about confirming the medical conditions of the patients who request it.









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How cannabinoids offer pain relief is still unclear, but several possible mechanisms have been theorized. Two cannabinoid (CB) receptors have been identified. CB₁ receptors are located throughout the central and peripheral nervous systems and many other tissues, while CB₂ receptors are primarily limited to immune tissue, including the spleen, tonsils, B cells, and T cells.⁵ It is thought that activation of CB₁ receptors may alter pain pathways, although the mechanism is unclear. These receptors are also linked to calcium and potassium channels, alterations of which have been implicated in the development of neuropathic pain.



Other potential sites of analgesia include the effects of cannabinoids on various serotonin receptors, anti-inflammatory effects mediated through the inhibition of prostaglandin synthesis, the inhibition of glutamate release by presynaptic nerves, and an increase in dynorphin release.