Study Suggests Synergism Between Medical Marijuana and Opiates
Posted by Dr. Julia Harder
In a paper published this month in Clinical Pharmacology & Therapeutics, researchers from UCSF examined the interaction between cannabinoids (the main ingredient in medical marijuana) and opiates in the first human study of its kind. They found the combination of the two components reduced pain more than using opiates alone, similar to results previously found in animal studies.
The primary endpoint of this small-scale study (21 patients) was to determine whether the use of medical marijuana would increase, decrease, or have no effect upon plasma levels of morphine and oxycodone in patients taking these opioids routinely for chronic pain. Of the 21 patients, 10 were taking extended-release morphine and 11 were taking extended-release oxycodone. After obtaining opiate blood levels at the start of the study, the patients inhaled a controlled amount of vaporized cannabis three times daily for four consecutive days. On the fifth day, they again measured opiate blood levels. In the process, researchers also asked patients about their pain relief. What they found was surprising.
On day 5, blood levels of morphine were slightly lower than they had been at the start of the study, and the levels of oxycodone were unchanged. However, the morphine group experienced a statistically significant reduction in average pain score from 35 to 24 (33% reduction), and the oxycodone group’s average pain score dropped from 44 to 34 (20% reduction). Patients did not experience any major side effects. Researchers concluded that vaporized cannabis augments the analgesic effects of opioids without significantly altering plasma opioid levels. The combination may allow for opioid treatment at lower doses with fewer side effects—which would benefit many of our hospice patients.
These results are only a first step toward understanding the role of medical marijuana in the treatment of chronic pain. According to Donald Abrams, MD, the paper’s lead author, “What we need to do now is look at pain as the primary endpoint of a larger trial,” he said. “Particularly I would be interested in looking at the effect of different strains of cannabis.”
Marijuana contains about 70 compounds which have different effects. Delta-9 tetrahydrocannabinol (Delta-9 THC) is the main psychoactive component, responsible for the “high” associated with marijuana. As the active ingredient in the drug dronabinol (Marinol®), delta-9 THC helps treat chemotherapy-induced nausea/vomiting and stimulate appetite, but it has only mild pain-relieving properties. It also has potential side effects such as tachycardia, confusion, anxiety and paranoia. Cannabidiol (CBD) is a major, non-psychoactive component of cannabis that helps reduce pain and inflammation without inducing euphoria.
“I think it would be interesting to do a larger study comparing high THC versus high CBD cannabis strains in association with opiates in patients with chronic pain and perhaps even having a placebo as a control,” Abrams said. “That would be the next step.”
Reference:
Abrams DI, Couey P, Shade SB, Kelly ME, Benowitz NL. Cannabinoid-Opioid Interaction in Chronic Pain. Clinical Pharmacology & Therapeutics 2011; 90: 844-851.
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