Marijuana for Arthritis and Pain: Is There a Role?

Bret S. Stetka, MD

Disclosures

June 25, 2014

In This Article

Human Studies in Rheumatic Disease

Moving on to studies in humans that have looked at cannabis as a therapy in rheumatic disease, Fitzcharles highlighted the fact that there is a very limited body of data to go on. One study examined medical marijuana in rheumatoid arthritis, 5 have been conducted in fibromyalgia, and there isn't a single randomized controlled trial of cannabis in any rheumatic disease.

The rheumatoid arthritis study,[4] published in 2006 in Rheumatology, reported that Sativex® -- a cannabis-based medicine -- produced statistically significant improvements in multiple pain measures in 58 patients over 5 weeks. The investigators acknowledged that the differences were small yet probably clinically relevant, and that there were no adverse event-related withdrawals or serious adverse events in the active treatment group.

Two studies looked at the synthetic THC nabilone in fibromyalgia. The first[5] was a randomized controlled trial of 40 patients; at 4 weeks, treatment was associated with significant decreases in the visual analog scale for both pain and anxiety. There were no significant improvements in the placebo group. Side effects were minimal, though more frequent, in the treatment group -- particularly drowsiness. The other study of nabilone[6] was conducted by Fitzcharles' group in Montreal and determined the agent to be equivalent to amitriptyline in improving sleep in patients with fibromyalgia, while also being well tolerated.

Other recent work[7] associated cannabis inhalation with a significant reduction in pain and stiffness, enhanced relaxation, and -- perhaps not surprisingly -- an increased feeling of well-being. A small study[8] of 9 patients looked at the efficacy of oral THC on electrically induced pain, axon reflex flare, and psychometric variables. Five of the participants withdrew owing to adverse side effects. Although THC had no effect on axon reflex flare, patients' daily recorded pain was significantly reduced. The investigators concluded that the unaffected electrically induced axon reflex flare, but decreased pain perception, suggests a central mode of action of the THC.

Finally, another study by Fitzcharles and colleagues[9] sought to provide epidemiologic clarity on cannabis use in fibromyalgia. Among 457 patients with the diagnosis, 13% were using cannabinoids, of whom 80% were using herbal cannabis (marijuana). The investigators concluded, "Although cannabinoids may offer some therapeutic effect, caution regarding any recommendation should be exercised pending clarification of general health and psychosocial problems, especially for those self-medicating."

Fitzcharles then walked the audience through some background data. In the United States, 10% of patients seen in chronic pain clinics use cannabis medicinally. Furthermore, she continued, 65% of those registered in Canada's medical marijuana access program report having severe arthritis.

Next up was a short botanical chemistry lesson. "Marijuana" typically refers to the leaves and buds of the Cannabis sativa plant and contains at least 60 cannabinoid molecules and around 100 noncannabinoid compounds. Pharmacologically, it's a complicated plant.

Where Do Clinicians Stand?

What does the medical community think about using marijuana as medicine? Fitzcharles presented data showing that in Colorado -- where both medicinal and recreational marijuana use are now legal -- 2% of the state's population were registered for medical marijuana in 2012.[10] However, these findings come with a major red flag: 50% of physician marijuana recommendations came from just 15 prescribers. When polled, only 20% of Colorado physicians felt there was a medical role.[11] Relatedly, Fitzcharles and her group polled Canadian rheumatologists,[1] 75% of whom reported being uncomfortable about their knowledge around the effects of cannabinoids on the human body and their potential medical uses.

Of note, a Medscape survey from earlier this year of 1544 US physicians reported somewhat different results:

  • 69% say it can help with certain treatments and conditions;

  • 67% say it should be a medical option for patients;

  • 56% support making it legal nationwide;

  • 50% of doctors in states where it is not legal say it should be legal in their states and

  • 52% of doctors in states considering new laws say that it should be legal in their states.

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