Study looks at varying T.H.C. in edible marijuana

Jun 23, 2015, 9:54 PM EDT
Marijuana products and paraphernalia are displayed at the Cannabis World Congress Expo on June 19, 2015 in New York City.
Andrew Burton/Getty Images

A paper published this morning in JAMA: The Journal of the American Medical Association raises questions about the amounts of T.H.C. in edible marijuana often prescribed for medical conditions. The study suggests that there has not been enough research into doses. CBS News reports:

Medical marijuana is prescribed to treat a variety of symptoms from chronic medical conditions -- everything from pain to nausea to muscle spasms -- but its effectiveness for specific uses is not entirely clear, according to a new analysis.
Researchers reviewed nearly 80 randomized trials that included about 6,500 participants. They found moderate-quality evidence to support the use of cannabinoids -- chemical compounds that are the active principles in marijuana -- for the treatment of neuropathic or cancer pain and spasticity due to multiple sclerosis. But when it came to cannabinoid use to treat nausea and vomiting due to chemotherapy, sleep disorders, weight gain in HIV, and Tourette syndrome, the evidence they found was lower quality.
The analysis, published today in the Journal of the American Medical Association (JAMA), also found an increased risk of adverse side effects, including dizziness, dry mouth, nausea, fatigue, somnolence, euphoria, vomiting, disorientation, drowsiness, confusion, loss of balance, and hallucination.
Edible marijuana-infused products – baked goods, beverages, and candy or chocolate – are popular with both medical and recreational users in states that allow their sale. About one-fifth of medical users depend on edibles nationwide, while nearly half of Colorado’s recreational sales have been for the products. While alleviating the need to smoke the plant material, edible products suffer from erratic absorption and delayed time to the onset of medicinal effects. Hence, aiming to start with a standardized, verified dose is an important step in predictable clinical treatment and research validity.
The researchers recruited physician-authorized buyers to representative products from medical marijuana dispensaries in San Francisco, Los Angeles, and Seattle. The researchers then had an analytical testing laboratory determine the amount of active cannabinoids in each product. They focused on THC, the primary active component of cannabis, and CBD, or cannabidiol, another plant chemical with medicinal properties that complement those of THC. Research with a standardized cannabis extract product undergoing clinical trials, Sativex, indicates that a 1:1 ratio of THC to CBD is most desirable medical indications such as the muscle spasticity of multiple sclerosis.
The most prominent problem was that products contained far less THC than advertised – an average of 47 percent less than indicated on the label. But some products contained almost no THC. At the other end of the spectrum, those products with more THC averaged 28 percent more than the labeled amount. A buyer was more likely to find a substandard product when purchased in Los Angeles while products with more THC than labeled were more likely to be found in Seattle.