Adding Cannabis to Opiates Treatment May Increase Pain Relief

Patients with chronic pain may experience greater relief if their physicians add cannabinoids—the primary ingredient in cannabis—to an opiates-only treatment, according to a study from the University of California at San Francisco (UCSF) Medical Center.

The findings, which are published in the December issue of Clinical Pharmacology & Therapeutics, also indicate that a combined therapy could result in reduced opiate dosages.

“Pain is a big problem in America and chronic pain is a reason many people utilize the health care system,” said the paper’s lead author, Donald Abrams, MD, in a statement. “And chronic pain is, unfortunately, one of the problems we’re least capable of managing effectively.”

In the study, researchers examined the interaction between cannabinoids and opiates in chronic pain patients. They found the combination of the two components reduced pain more than using opiates alone, similar to results previously found in animal studies.

Researchers studied chronic pain patients who were being treated with long-acting morphine or long-acting oxycodone. Their treatment was supplemented with controlled amounts of cannabinoids, inhaled through a vaporizer.

The original goal of the study, according to Dr. Abrams, was to determine whether inhalation of cannabis affected the level of the opiates in the bloodstream. “The way drugs interact, adding cannabis to the chronic dose of opiates could be expected either to increase the plasma level of the opiates or to decrease the plasma level of the opiates or to have no effect,” he noted. “And while we were doing that, we also asked the patients what happened to their pain.”

The researchers studied 21 chronic pain patients: 10 on sustained-release morphine and 11 on oxycodone. After obtaining opiate levels from patients at the start of the study, researchers exposed them to vaporized cannabis for 4 consecutive days. On the fifth day, they reexamined the level of opiate in the bloodstream. Because the level of morphine was slightly lower in the patients, and the level of oxycodone was virtually unchanged, “one would expect they would have less relief of pain and what we found that was interesting was that instead of having less pain relief, patients had more pain relief,” Dr. Abrams said. “So that was a little surprising.”

The morphine group came in with a pain score of about 35, and on day 5 it decreased to 24—a 33% reduction. The oxycodone group demonstrated an average pain score of about 44, which reduced to 34—a drop of 20%. Overall, patients showed a significant decrease in their pain.

“This preliminary study seems to imply that people may be able to get away perhaps taking lower doses of the opiates for longer periods of time if taken in conjunction with cannabis,” Dr. Abrams said. “What we need to do now is look at pain as the primary endpoint of a larger trial. Particularly I would be interested in looking at the effect of different strains of cannabis.”