Pharmacology

Can cannabis relieve pain?

Anaesthetist Pierre Beaulieu is conducting clinical research at the Centre hospitalier de l’Université de Montréal (CHUM) on nabilone, a synthetic derivative of THC (tetrahydrocannabinol), the main psychoactive ingredient in cannabis. The first of its kind in Canada, the research focuses on post-operative pain and the analgesic properties of cannabis taken in combination with morphine in patients who have undergone major surgery. “Our hypothesis is that nabilone, taken in combination with morphine, is more effective than widely used pain medications such as non-steroid anti-inflammatory medication or NSAIDs,” explains Dr. Beaulieu who, in addition to his medical practice, is a professor in the Université de Montréal’s Department of Pharmacology.

Of course, the protocol does not involve bed-ridden patients passing around a joint. Instead, patients would take tablets made from the synthetic molecule derived from cannabis. “When you smoke a joint, some 60 cannabinoid products are absorbed into the blood, some of which have psychotropic effects. Nabilone is only one of these products.”

Subjects will receive three doses of nabilone in addition to morphine every 24 hours, and the effects will be compared to those obtained from a placebo and another widely used NSAID product also administered in conjunction with morphine. Of the 160 patients Dr. Beaulieu plans to recruit for his study, over 40 have already agreed to participate.

The use of marijuana for medicinal purposes in very specific circumstances is legal in Canada. For several years, doctors have been prescribing cannabis to their patients to relieve pain. Two other prescription medications are also available. In addition to nabilone (sold under the brandname Cesamet), used mainly to relieve nausea, another cannabinoid derivative, dronabinol (brandname Marinol), is also prescribed to stimulate appetite in anorexics. But clinical practitioners are not unanimous on the use of these two derivatives, which have not been designated for the treatment of pain. Yet, cannabis has long been used in laboratories for a long time. The effects of THC on animals have been proven. But according to Dr. Beaulieu, who recently conducted an exhaustive literature review on the subject, cannabis has been gaining ground over the last 18-24 months in the world of medicine.

But why the search for new pain medication? Surprisingly, there are very few analgesics in the therapeutic arsenal. There is acetaminophen (or Tylenol) to relieve mild pain, and morphine and its derivatives to relieve acute pain. “There’s virtually nothing in between. And now we’re seeing the limitations of prescribing NSAIDs. As for morphine, it may be effective, but it also has significant side effects.”