Cannabis for MS – an update
Cannabis has a limited effect on symptoms of multiple sclerosis, according to a new review of 17 studies involving over three thousand people with MS (Torres-Moreno and colleagues. JAMA Network Open 2018;1:e183485; free full text at https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2706499).
One of the challenges to determining the benefits and risks of cannabis is the range of products available, which contain differing amounts of the active ingredients. The Cannabis plant contains hundreds of chemicals. Of importance to MS are the cannabinoids, which interact with the endocannabinoid system in the brain and peripheral nervous system. The two main cannabinoids are THC (tetrahydrocannabinol) and CBD (cannabidiol). Synthetic formulations include dronabinol (THC, brand name Marinol), which is a capsule taken orally; nabilone (THC, brand name Cesamet); the nabiximols (THC/CBC, brand name Sativex), taken as an oral spray; and cannabis extract (THC/CBD, brand name Cannador), which is an oral capsule. [Products are not available in all countries.] Smoked cannabis hasn’t been studied extensively in MS and determining its risks and benefits will be difficult because of the countless strains that have been developed containing differing amounts of THC and CBD.
Assessing the effects of cannabis is made even more complicated by the many ways it can be taken. When smoked, more active drug is available to the body and the effects are more immediate because the drug enters the brain before it is broken down by the liver. The lowest amount of drug is delivered more slowly when cannabis goes through the gastrointestinal tract (as an oral capsule or as an edible) since the liver breaks down about 95% of the drug before it enters the blood stream.
The drugs included in the cannabis review were dronabinol, nabilone, nabiximols, and cannabis extract. Smoked cannabis wasn’t included. Here is a summary of the findings for MS symptoms:
Spasticity (muscle tightness and spasms): People taking cannabis extract, nabiximols and CBD reported a modest effect (about a 25% improvement); there was no significant effect with dronabinol. Doctor assessments found a very slight improvement in spasticity (about 9%).
Pain: There was a significant improvement in pain with cannabis extract, nabilone, and CBD (a 17% improvement overall).
Bladder problems: There was a significant improvement with cannabis extract (29%), but not with dronabinol or nabiximols (6-7%, which didn’t differ from a placebo).
One concern expressed by the researchers was that many of the studies were funded by drug companies. When these studies were excluded from the analysis, nabilone didn’t appear effective for pain, CBD didn’t appear effective for bladder problems, and nabiximols didn’t appear to be effective for any of the MS symptoms under study.
Cannabis did appear to be safe. Most people experienced some side effects but there were few serious events. The most common side effects were dizziness, dry mouth, fatigue, feeling drunk, balance problems, memory impairment, and sleepiness.
The authors concluded that cannabis has limited benefits in relieving MS symptoms. A similar conclusion was made in a number of previous reviews of the topic (Wade and colleagues. Mult Scler 2010;16:707-714. Iskedjian and colleagues. Curr Med Res Opin 2007;23:17-24. Whiting and colleagues. JAMA 2015;313:2456-2473). Two reviews found that cannabinoids were beneficial (Meza and colleagues. Medwave 2017;17(suppl 1):e6865. da Rovare and colleagues. Complement Ther Med 2017;34:170-185).
To access a review of cannabis by the U.S. National MS Society, click
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