Regulatory authorities in Canada have signed off on a new cannabis-based treatment for certain symptoms of multiple sclerosis, making that country the first in the world to approve a marijuana-based drug as an MS therapy. On April 19, Health Canada approved the use of a cannabis-extract, Cannabis sativa L., in oral spray form as an adjunctive treatment to relieve neuropathic pain associated with MS.
Therapy to be Available This Summer
According to the Multiple Sclerosis Society of Canada,1 the drug will be marketed as Sativex, and will reportedly be available for Canadians by this summer. It consists of various extracts from the marijuana plant known as cannabinoids. The approval makes Canada the first country anywhere to legalize a cannabis compound as a therapy for MS. However, the approval came with a stipulation that more studies must be conducted to confirm the apparently positive clinical results seen thus far.
The regulatory approval of the medication was based on a small, four week clinical trial that took place in the UK. The study, sponsored by GW Pharmaceuticals, which makes Sativx, involved 66 people diagnosed with multiple sclerosis who had complained of central neuropathic pain. Half of the patients were selected to receive the drug in spray form, while the rest received a placebo.
The investigators found that those in the group taking Sativex used fewer doses of the spray throughout the study as compared to their counterparts in the placebo group. Those in the treatment group also reported experiencing less pain, improved sleep, and a feeling that their condition had improved compared to those given the placebo intervention.
Reported side effects included vertigo, nausea and fatigue.
Cannabinoid Controversy
While marijuana use or possession is illegal in the United States, its backers tout the plant's ability to treat pain and nausea. Cannabinoids, which the newly approved MS drug in Canada contains, are being evaluated by medical researchers to determine how effective they might be in controlling symptoms of certain medical conditions.
Cannabinoids consist of compounds known as THC, cannabinol, cannabidiol, and dronabinol. THC is the main component in marijuana responsible for its mind-altering effect. It may also be the component responsible for treating some disease symptoms. Cannabinol and cannabidiol have similar properties as THC, but don't affect the brain as acutely. Dronabinol is a synthetic version of THC available by prescription, and is used to prevent nausea and vomiting associated with chemotherapy. It's also believed to help boost appetite in people with HIV. These components work by targeting and attaching to certain cell receptors in the brain. Receptors are components of a cell that, when attached to other compounds or microbes in the body, activate the cell in a certain way. While these receptors aren't well understood in the context of cannabinoid treatment, it's believed that they may be part of the process of immune suppression, which in turn, could suppress some symptoms of MS.2
Research in the States
Here in the United States, cannabinoids have been the focus of a medical experts as a potential therapy for MS, even though they aren't approved by the FDA. So far, experts have only been taking part in or reading about studies on this compound. In 2003, doctors in England unveiled a trial of 600 MS patients comparing oral doses of cannabis extract, synthetic THC, or a placebo.3
The researchers led by John Zajicek, MD, wrote that nearly two-thirds of the patients in both extract groups reported improvements in spasticity, a type of MS-associated spasm, and less pain. And while the study lasted about 4 months, Zajicek announced there were apparently longer-term benefits for the patients who continued the therapy for up to one year.
But cannabis may not treat all MS-related symptoms. In an earlier study of just 14 patients, British scientists learned that extracts of the plant had no effect on tremor in people with the disease.4
1. Multiple Sclerosis Society of Canada. Health Canada Approves Sativex for Treatment of MS-Related Pain. Available at: http://www.mssociety.ca/en/research/meddmmo-marij-sativex-apr05.htm. Accessed May 20, 2005.
2. Mayo Foundation for Medical Education and Research. Marijuana as Medicine? Available at: http://www.mayoclinic.com/invoke.cfm?id=GA00014. Accessed May 20, 2005.
3. Zajicek J, Fox P, Sanders H et al. Cannabinoids for treatment of spasticity and other symptoms related to multiple sclerosis (CAMS study): multicenter randomized placebo-controlled trial. Lancet 2003 Nov 8;362(9395):1517-26.
4. Fox P, Bain PG, Glickman S, Carroll C, Zajicek J. The effect of cannabis on tremor in patients with multiple sclerosis. Neurology 2004 Apr 13;62(7):1105-9.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
