By Pat Anson, Editor

The American Medical Association, the nation’s largest medical group, still officially considers medical marijuana “a dangerous drug and as such is a public health concern."

But studies being published this week in JAMA, the AMA’s official journal, highlight the slim but growing body of evidence that cannabis can be used to treat pain – as well as the lack of standards regulating medical marijuana in states where it is legal.

In a review of nearly 80 clinical trials involving over 6,400 patients, researchers found “moderate-quality evidence” that cannabinoids –  chemically active compounds in marijuana – are effective in treating chronic neuropathic pain and cancer pain, as well as muscle spasms and stiffness caused by multiple sclerosis.

There was “low-quality evidence” suggesting that cannabinoids are effective in treating sleep disorders, weight loss, Tourette syndrome, and symptoms of nausea and vomiting caused by chemotherapy; and “very low-quality evidence” for treating anxiety.

Some of the side-effects associated with medical marijuana were dizziness, dry mouth, nausea, fatigue, somnolence, euphoria, vomiting, disorientation, drowsiness, confusion, loss of balance, and hallucination.

"Further large, robust, randomized clinical trials are needed to confirm the effects of cannabinoids, particularly on weight gain in patients with HIV/AIDS, depression, sleep disorders, anxiety disorders, psychosis, glaucoma, and Tourette syndrome are required. Further studies evaluating cannabis itself are also required because there is very little evidence on the effects and AEs (adverse events) of cannabis," the authors write.

An accompanying editorial in JAMA also called for more research and lamented the lack of evidence supporting the legalization of medical marijuana in 23 U.S. states and the District of Columbia.

"If the states' initiative to legalize medical marijuana is merely a veiled step toward allowing access to recreational marijuana, then the medical community should be left out of the process, and instead marijuana should be decriminalized," wrote Deepak Cyril D'Souza, MD, and Mohini Ranganathan, MD, of the Yale University School of Medicine.

"Conversely, if the goal is to make marijuana available for medical purposes, then it is unclear why the approval process should be different from that used for other medications… Since medical marijuana is not a life-saving intervention, it may be prudent to wait before widely adopting its use until high-quality evidence is available to guide the development of a rational approval process."

The Trouble with Edibles

A second study published in JAMA looked at marijuana edibles – cookies, brownies, candies and other foods containing cannabis – that are being sold at dispensaries in Los Angeles, San Francisco and Seattle.

An estimated 16% to 26% of cannabis patients consume edibles. Many are essentially homemade products that vary from dispensary to dispensary.

Researchers found that many of the edibles had lower amounts of THC (tetrahydrocannabinol) – the active ingredient in marijuana that makes people “high” – than their labels indicated. Over half had significantly higher amounts of THC, putting patients at risk of unintended side-effects.

Of the 75 edible products that were analyzed in a laboratory, only 17% were accurately labeled with THC, 23% were “overlabeled” and 60% were “underlabeled.” The greatest likelihood of obtaining an underlabeled edible was in Seattle.

A little over half (59%) of the edibles tested had detectable levels of cannabinoids.

"Edible cannabis products from 3 major metropolitan areas, though unregulated, failed to meet basic label accuracy standards for pharmaceuticals," the authors write. "Because medical cannabis is recommended for specific health conditions, regulation and quality assurance are needed."

The lack of regulation was highlighted last year in Colorado – where both medical and recreational use of marijuana is legal. A brand of brownie mix, Rice Krispy treats and candy made with cannabis was recalled after inspectors found the edibles contained marijuana that had been “cleaned” in a washing machine.