Medical Cannabis Shows Promise in Reducing Opioid Misuse, Finds New Review
Medical cannabis shows promise in lessening opioid use and potential abuse, say the authors of a new systematic review presented this week at the Anesthesiology 2019 annual meeting.
Of the key studies identified by the review, a majority concluded that medical cannabis use could be associated with benefits such as decreased opioid use, decreases rates of opioid overdose, improved pain control, and improvements in overall quality of life.
However, despite their findings, the review’s authors stress that more research must to be done to truly determine the effectiveness of medical cannabis as an alternative to pain-reliving opioid medications, and to identify any possible ill effects that might arise with long-term use.
Medical cannabis: a positive but “weak to moderate” effect on opioid use
The researchers, from the Rush University Medical Center in Chicago, IL, conducted a literature review and meta-analysis with the search terms “opioid,” “cannabis,” “cannabinoid,” and “marijuana” across an extensive library of scientific articles published between 2010 and 2018.
Their search provided 30 relevant studies, seven of which provided all the information needed to study any link between cannabis legalization and opioid misuse. Of these seven studies, five showed links between medical cannabis use and the mitigation of opioid abuse.
These five studies had several positive findings; there was a 29 percent reduction in opioid overdoses in states with legal medical cannabis and a 44-64 percent reduction in opioid use among chronic pain patients.
The other studies found no evidence of an overall reduction in opioid use.
On the whole, the researchers calculated the effect of the seven combined studies to be 0.59, meaning that medical cannabis has a “weak to moderate” beneficial effect. For this type of research, any value calculated below 0 shows a negative effect, above zero is a positive effect, and above 1 demonstrates a strong positive effect. The positive effect from medical cannabis use was also shown by the researchers to be statistically significant.
Not an immediate fix
While the review and meta-analysis does appear to imply the existence of a link between cannabis use and decreased rates of opioid abuse, the authors acknowledge that much more research will be needed before cannabis can be formally recommended as an alternative or adjunct therapy to opioid medications.
“Overall the results suggest medical marijuana may provide some benefit in mitigating opioid misuse, but the studies were not randomized controlled trials comparing marijuana to a placebo, which is what we need to determine a true benefit,” said Mario Moric, a biostatistician at Rush University Medical Center and the lead author of the study, in a statement.
“There are other issues to consider as well, including side effects and the fact that these products often aren’t regulated,” Moric added.
Asokumar Buvanendran, co-author of the study and chair of the American Society of Anesthesiologists Committee on Pain Medicine, cautioned that further research into the side effects of long-term cannabis use still need to be investigated before medical cannabis could be considered an alternative to opioid treatment.
“Long-term effects of medical marijuana are not known and haven’t been studied yet,” he said. “Early clinical evidence suggests that marijuana might have detrimental effects on the brain.”
Both authors also noted that studies that report positive results are more likely to be published than those with negative results, and this could skew the results of their systematic review.
The trouble with opioid medications
While opioid medications are hugely effective painkillers for short bouts of treatment, their long-term use by those with chronic pain must be carefully managed to avoid patients developing a dependence or an addition to the medication.
Opioids contribute to more than 70,000 people per year in the US. This growing toll prompted the Acting Secretary of Health and Human Services to officially declare the opioid crisis a public health emergency in 2017.
While the illicit use of opioid drugs does play its part in this epidemic, the major contributing factor to the development of opioid use disorders is thought to be the over-prescription of opioid medications by doctors.
As a result, finding an opioid alternative that can provide the same pain-relief but for patients but remain safe for long-term use is a key part of tackling the nation’s problems with opioid addiction.
Medical cannabis became a particular focus for this area of research as cannabinoid-1 (CB1) receptors and mu opioid receptors (MORs) have been shown to be present in many of the same areas of the brain, and both mechanistically act largely through the same group of G-proteins. While the exact neurobiological mechanisms between any interaction of these receptors remains unknown, the possibility that cannabis receptors could modulate the body’s response to opioids has led to its consideration as a potential treatment for opioid use disorder, and as an outright alternative to opioid medications.
