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Marijuana Trials Leave RA Patients in Doubt

June 6, 2014
Lack of dosing guidelines, plant-based differences in THC levels—which can lead to over- or under-dosing—and safety of inhaled products remain.

Medical marijuana, although effective for some types of pain, does not appear to relieve chronic pain in patients with rheumatoid arthritis. According to a recently published paper in the journal Arthritis Care & Research, there is a lack of published studies to support the use of  medical marijuana to relieve chronic pain caused by inflammation, as seen with most arthritis patients.1

According to the American College of Rheumatology (ACR), rheumatoid arthritis is an autoimmune disease, in which the body's own immune cells attack the synovium—the tissue that lines the joints—causing inflammation, stiffness, and pain.  Rheumatoid arthritis is the most common form of autoimmune arthritis, noted the association, "affecting more than 1.3 million Americans. Of these, about 75% are women. In fact, 1% to 3% of women may get rheumatoid arthritis in their lifetime." 

The recent push to legalize and decriminalize marijuana has led some physicians to question: Is this good for medicine? Not necessarily so, argues Mary-Ann Fitzcharles, MD, of  McGill University in Montreal, Canada, and colleagues in the recent article. Dr. Fitzcharles and colleagues cite a lack of studies proving the effectiveness of medical marijuana and regulations for proper dosing, as well as the risks associated with marijuana consumption, especially through smoking.

"The recent advocacy for marijuana legalization or decriminalization should prompt practitioners to warn their patients about the risks of marijuana use," they noted. “Simply acceding to patient demands for a treatment on the basis of popular advocacy, without comprehensive knowledge of an agent, does not adhere to the ethical standards of medical practice,” Dr. Fitzcharles and colleagues wrote.

The Push to Legalize

Although still considered a schedule I drug by the Federal government, medical marijuana is currently legal in 20 states. Recent legalization and decriminalization of recreational marijuana in cities like Denver and Seattle have prompted more state legislators to consider further changing the current laws. 

Marijuana contains a chemical called tetrahydrocannabinol (THC) that is responsible for giving users the euphoria, pain relief, sleepiness, and increased appetite commonly associated with the drug.

Dr. Fitzcharles and colleagues stated that despite recent changes in the law, most marijuana users are still obtaining the drug illegally. Of major concern is the lack of knowledge concerning the chemical properties of different forms of marijuana, as strains of the plant can vary widely in THC levels—from 1% to 30% concentration levels. Individuals that inhale the drug through smoking can have a wide range of  THC levels in their bloodstream, some as low as 7 ng/mL to as high as 100 ng/mL.

“Therefore, the lack of the most elementary requirements for responsible drug administration must call into question any use of herbal cannabis for rheumatic pain treatment at this time,” the authors stated.  

Small Sample of Clinical Studies

Studies of the use of medical marijuana as a treatment for rheumatoid arthritis do exist. Researchers at the British Royal National Hospital for Rheumatic Disease reported positive results back in 2006 when they conducted the first ever trial of using cannabis-extracts to treat rheumatoid arthritis. After the 5-week study, they reported significant improvements in movement, rest, and intensity pain types, as well as improved sleep and decreased inflammation."A significant analgesic effect was observed and disease activity was significantly suppressed following Sativex treatment," wrote the researchers.

A second study was conducted by GW Pharmaceuticals, the manufacturer of nabiximol (Sativex), a cannabis-based medicine that is currently undergoing review by the Food and Drug Administration. The drug comes in the form of a mouth spray and is intended for cancer-based pain treatment. The company's own trial on rheumatoid arthritis patients reported positive results.

Other trials are examing other forms of cannabinoids. However, few studies exist on plant-based efficacy for rheumatic diseases, according to Dr. Fitzcharles. 

Despite the lack of research, “severe arthritis” is a common ailment associated with marijuana use. In a recent survey, two thirds (or 65%) of Canadians who said they use medical marijuana are prescribed the medicine for arthritis, according to Dr. Fitzcharles and colleagues. Twenty-five percent  of medicinal marijuana patients in Australia and 20% of respondents in Britain have cited arthritis as their reason for using the drug.3,4

“While there is good evidence for the efficacy of cannabanoids for treating some chronic pain conditions, such as cancer and neuropathic pain, these pain types have different underlying mechanisms from the mostly peripheral/nociceptive pain in rheumatic diseases,” the researchers wrote.

Hazards of Marijuana

Marijuana use is associated with numerous side effects, including its effects on cognitive functioning, short-term memory, motor control, and other negative cognitive and psychomotor effects that can impair patients’ driving abilities. Marijuana use has also been associated with depression, dependency, and paranoia. A National Institute on Drug Abuse (NIDA) review indicated that 9% of first-time users of marijuana will become “addicted.”5

Mental health risks of regular marijuana use include:

  • Increase likelihood of anxiety and depression
  • Increased likelihood of psychosis
  • Worsened symptoms of schizophrenia
  • Earlier onset of psychotic events.

Smoking marijuana is also believed to lead to a two-fold increase in the risk of developing lung cancer.6

Last updated on: May 19, 2015