United States – The evidence for the effectiveness of cannabis-related products for the treatment of chronic pain is so far flimsy. According to a new systematic scientific review by researchers at Oregon Health & Science University, products with high levels of THC may help treat neuropathic pain.
Researchers have found evidence for a short-term benefit in the treatment of neuropathic pain – caused by damage to peripheral nerves, such as diabetic neuropathy resulting in pain described as burning and tingling. The study involved products containing 100 percent THC: dronabinol (Marinol) and nabilone (Cesamet).
Both products also lead to notable side effects, including sedation and dizziness, according to the review.
Another product, a sublingual spray of equal parts THC and cannabidiol (CBD) extracted from the cannabis plant – known as nabiximols – also showed evidence of some clinical benefit for neuropathic pain, although that product is not available in the US.
Little hard evidence for the effect of cannabis products
“Overall, the limited amount of evidence surprised us all,” said lead author Marian S. McDonagh, Pharm.D., professor emeritus of medical informatics and clinical epidemiology at the OHSU School of Medicine. “With so much buzz around cannabis-related products and the ready availability of recreational and medicinal marijuana in many states, consumers and patients might assume there would be more evidence about its benefits and side effects.
“Unfortunately, there is very little scientifically valid research on most of these products. We saw only a small group of observational cohort studies on cannabis products that would be readily available in states that allow it. These were not designed to answer the important questions about chronic pain management.”
Voters in Oregon, Washington and 20 other states have legalized medical and recreational marijuana, but the researchers found that many of the products now available at U.S. dispensaries have not been properly studied. “For some cannabis products, data is sparse with inaccurate estimates of effect. Studies sometimes had methodological limitations,” the authors write.
“Cannabis products vary quite a bit in their chemical makeup, and this can have important benefits and harm effects for patients,” said co-author Roger Chou, MD, director of OHSU's Pacific Northwest Evidence-based Practice Center. “That makes it difficult for patients and clinicians, because the evidence for one cannabis-based product may not be the same for another.
Source: neurosciencenews.com (EN)