A new study aimed at comparing medical marijuana and opioids for chronic non-cancer pain found that cannabis “may be similarly effective and result in fewer discontinuations than opioids,” potentially offering comparable relief with a lower likelihood of adverse effects.
The findings, published in the journal BMJ Open, come from a review of 90 randomized controlled trials (RCTs) comparing opioids, medical marijuana and placebos, which together involved 22,028 participants. Eighty-four of the trials were included in the report’s qualitative analysis.
“Our findings suggest that both opioids and cannabis for medical use may provide benefits for a minority of chronic pain patients,” the study says. “Furthermore, Marijuana does not cause respiratory depression which can result from opioids consumption and lead to non-fatal or fatal overdose.”
Authors say the study is the first network meta-analysis “exploring the comparative effectiveness of cannabis for medical use and opioids for chronic non-cancer pain.”
Chronic pain, which impacts about 20 percent of people globally, is commonly treated with opioids, authors noted. And while they found “moderate” evidence that opioids provide small improvements in pain, they found “low to moderate certainty evidence” that marijuana has similarly positive effects.
“Low certainty evidence from 82 RCTs involving 19 693 patients suggested that there may be little to no difference in pain relief between cannabis for medical use and opioids,” the study says.
And while both opioids and marijuana “probably result in higher discontinuations compared with placebo,” participants using opioids seemed to quit treatment more frequently as the result of negative effects.
“Low to moderate certainty evidence suggests that cannabis for medical use may provide similarly small improvements in pain, physical function and sleep compared with opioids,” the study concluded, “and fewer discontinuations due to adverse events.”
Neither opioids nor marijuana appeared more effective than placebo for “role, social or emotional functioning,” the study found. Low-certainty evidence also suggested “there may be little to no difference in sleep quality” between the two substances.
The findings are promising but underscore the need for further study. Of the 24 medical marijuana trials in the review, for example, “none of these trials administered inhaled forms of cannabis and the generalisability of our findings to smoked or vaporized cannabis is uncertain,” wrote the nine-author team from McMaster University in Ontario, Canada. No smoking-related studies were included “due to inadequate duration of follow-up (<4 weeks),” they explained.
Moreover, researchers had to compare the effects of opioids and cannabis indirectly, since they found “only one trial directly comparing both interventions for chronic pain.”
As part of the evaluation, researchers categorized various trials by their quality of evidence. Most trials (75 out of 90, or 83 percent), they said, “were judged to be at high risk of bias for at least one domain.”
Those domains include random sequence generation; allocation concealment; blinding of participants, caregivers, outcome assessors and data analysts; and loss of participants to follow-up, the study notes.
Obstacles to cannabis research generally have contributed to issues of bias, in part by preventing blinding of study participants. In a recent study into cannabis and exercise, for example, participants were required to obtain their own state-legal cannabis because researchers couldn’t provide the substance directly. “State legislation requires that THC and CBD content be labeled on all commercially available products,” that study said, “and as such, participants were aware of the cannabinoid content of their assigned products.”
As for cannabis and pain, a growing body of research suggests that cannabinoids can help ease pain, in some cases offering benefits over opioids. A study last November, for example, found that marijuana and opioids were “equally efficacious” at mitigating pain intensity, but cannabis also provided more “holistic” relief, such as by improving sleep, focus and emotional wellbeing.
That same month, another study in the Journal of Dental Research found that pure CBD could alleviate acute dental pain about as well as an opioid formula commonly used in dentistry.
“Our results indicate that a single dose of CBD is as potent as current analgesic regimens and can manage emergency dental pain effectively,” the authors wrote in that study, adding that their work appears to be “the first randomized clinical trial testing CBD for managing emergency dental pain” and could eventually lead to FDA approval of CBD for dental pain.
For cancer-related pain, meanwhile, a study published earlier this year found that of cancer survivors who used medical marijuana as treatment, just over half (51 percent) used the drug to manage pain, with a strong majority of those patients reporting some level of benefit.
A separate study recently found that letting people buy CBD legally significantly reduced opioid prescription rates, leading to 6.6 percent to 8.1 percent fewer opioid prescriptions.
Another study, published last summer in the journal Cannabis, linked medical marijuana use to lower pain levels and reduced dependence on opioids and other prescription medications. Participants reported reduced pain and anxiety, improved physical and mental functioning, better sleep quality and mood and less reliance on prescription medications, including opioids and benzodiazepines.
Last month a study in the Journal of Endometriosis and Uterine Disorders found that CBD-infused tampons “achieved statistically significant pain reduction” in cases of severe cramps and menstrual pain, appearing to offer “fewer side effects than anti-inflammatories, while producing a similar pain-relieving effect.”
A forthcoming research project from Johns Hopkins University researchers, meanwhile, will track 10,000 medical marijuana patients over a year or more in an effort to better understand the efficacy and impacts of cannabis therapy.
Funded with a five-year $10 million grant from the National Institute on Drug Abuse (NIDA), the research team will work with federal researchers nonprofits to collect data around dosing, delivery methods, the chemical composition of products, possible medication interactions and other treatment details.
