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Herbal Cannabis Not Recommended for Rheumatology Patients

Report warns of inherent risks

Patients with rheumatic conditions are in need of symptom relief, and some are turning to herbal cannabis as a treatment option. However, the effectiveness and safety of medical marijuana to treat symptoms of rheumatic conditions, such as rheumatoid arthritis, lupus, and fibromyalgia, is not supported by medical evidence.

A new article published in Arthritis Care & Research explores the risks associated with using herbal cannabis for medicinal purposes and advises health care providers to discourage rheumatology patients from using this drug as therapy.

The reason for the medical interest in herbal cannabis is that the human body has an extensive cannabinoid system comprising molecules and receptors that have effects on many functions including pain modulation. Medical cannabis is commonly used to self-treat severe pain associated with arthritis and musculoskeletal pain. In fact, previous research has reported that 80% of marijuana users in a U.S. pain clinic were treating myofascial pain with the drug.

“With the public outcry for herbal cannabis therapy, governments around the world are considering its legalization for medicinal use,” explains lead investigator Dr. Mary-Ann Fitzcharles. “Physicians caring for patients who are self-medicating with marijuana need to understand the health implications of using this drug. Our study aims to provide health care professionals with that medical evidence related to medical marijuana use in patients with rheumatic conditions.”

In the U.S., 19 states and the District of Columbia have legalized cannabis for medical purposes. The new study examined the dosing, administration, efficacy, and risks of herbal cannabis in pain management for patients with rheumatic conditions. The health issues with recreational marijuana use in this patient population were not covered. Concentrations of tetrahydrocannabinol (THC) — the substance found in Cannabis sativa that provides pain relief and alters brain function — vary in the plant material by up to 33%, and absorption rates vary between 2% and 56%, making the dosing of herbal cannabis unreliable, the authors say.

Furthermore, no short- or long-term trials of the effectiveness of herbal cannabis have been conducted in patients with rheumatic diseases. Studies that show good efficacy of cannabinoids in cancer and neuropathic pain may not be extended to rheumatic diseases because of the differing mechanisms in the types of pain, according to the authors.

The new report emphasizes that the use of medical marijuana comes with inherent risks, such as compromised cognitive and psychomotor functions. Long-term use of cannabis may lead to mental illness, dependence, addiction, and memory issues, the report warns. In fact, a previous U.S. study of 8,000 adults who used cannabis in the previous year found that the odds of depression were 1.4 times higher in cannabis users compared with non-users.

“At this time, we cannot recommend herbal cannabis for arthritis pain management, given the lack of efficacy data, potential harm from the drug, and the availability of other therapies for managing pain,” the authors conclude. “Physicians should discourage rheumatology patients from using medical marijuana as a therapy.”

Source: Wiley; March 3, 2014.

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