Some responders
However, Dr. Attal acknowledged that cannabis might be effective for some patients. In her experience, which has been borne out by some observational studies, patients with paroxysmal pain, or sudden stabbing pain, seem to get more relief from cannabis. “It’s absolutely possible that there’s a subgroup of symptoms or a subgroup of patients with specific symptoms who are much better responders to cannabis than others,” she said.
Asked if patients experience increased pain after withdrawing from cannabis, Dr. Eisenberg said he has observed that many patients stop taking cannabis when they start feeling better, but he hasn’t seen severe withdrawal symptoms.
However, there are other concerns related to cannabis use, said Dr. Eisenberg. A major concern regards driving a vehicle. In Israel, getting behind the wheel is prohibited within 6 hours of using cannabis.
But Dr. Eisenberg pointed out that published data on the safety of cannabis and driving were based on recreational users. “We need to keep in mind that recreational users typically use other substances, so we’re not sure the data is accurate,” he said.
There are increasing reports of stroke, transient ischemic attack, and MI among cannabis users. This is especially concerning because many of these cases involve young male adults who have no risk factors, said Dr. Eisenberg.
One conference delegate asked whether legal issues make it difficult to properly investigate cannabis in large studies. Dr. Eisenberg noted that legal concerns may help explain why there have not been any new randomized, controlled trials for about 2 years. “In the U.S., you can’t do clinical trials; cannabis is still regarded as schedule I substance,” he said.
Some physicians “are reluctant to deal with cannabis unless they get better data,” he said. “Doing research on cannabis seems to be somehow out of the mainstream.” Moreover, the research is difficult to carry out, owing to the complexity of the cannabis plant, which has many constituents. Perhaps it’s a matter of identifying and adding particular components to better demonstrate reduced pain, said Dr. Eisenberg.
Another complicating factor is that bioavailability differs considerably from one patient to another, “sometimes even by 10-fold,” he said.
Dr. Attal’s group will be starting a study next January that will enroll a large sample of patients with neuropathic pain or spasticity. In that study, cannabis will be dispensed through pharmacies and primary care. The aim of the study is “to see how it works in a real-life setting,” she said
Those participating in the virtual session were asked to vote on which side they agreed with. About 57% voted in favor of cannabis use, 14% voted against, and 28% had no opinion.
Dr. Eisenberg has received research grants from Rafa Laboratories, Saga Medical Ltd., Israel Pain Association, and Teva Israel. Dr. Attal has received support from Merck Sharp & Dohme, Sanofi, Ipsen, Novartis, Aptinyx, Air Liquide, Lilly, and Grunenthal.
A version of this article originally appeared on Medscape.com.