Vaporized cannabis “significantly augments” the analgesic effects of opiates in patients with chronic pain, according to clinical trial data published online in 2011 in the scientific journal Clinical Pharmacology & Therapeutics. They found the combination of the two components reduced pain more than using opiates alone, similar to results previously found in animal studies.
“Pain is a big problem in America and chronic pain is a reason many people utilize the health care system,” said lead author Donald Abrams, M.D., professor of clinical medicine at UCSF and chief of the Hematology-Oncology Division at San Francisco General Hospital and Trauma Center (SFGH), reports Leland Kim at UCSF. “And chronic pain is, unfortunately, one of the problems we’re least capable of managing effectively.”
Researchers studied 21 chronic pain patients who were being treated with twice-daily doses of long-acting morphine or long-acting oxycodone, looking at their use of vaporized marijuana over a five-day period. The original focus was on whether the opiates’ effectiveness increased, not on whether the cannabinoids reduced pain.
After obtaining opiate levels from the patients at the start of the study, participants in the trial inhaled cannabis vapor on the evening of day 1 of the study, three times a day on days 2 through 4, and in the morning of day 5, reports the National Organization for the Reform of Marijuana Laws (NORML).
The extent of each patient’s chronic pain was assessed daily. On the fifth day, researchers looked again at the level of opiates 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,” Abrams said. “So that was a little surprising.”“The goal of the study really was to determine if inhalation of cannabis changed the level of the opiates in the bloodstream,” Abrams said. “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. And while we were doing that, we also asked the patients what happened to their pain.”
The morphine group came in with a pain score of about 35, and on the fifth day, it had decreased to 24 — a 33 percent reduction. The oxycodone group came in with an average pain score of about 44, and it reduced to 34m, falling 20 percent. Overall, patients, showed what researchers called a “significant decrease” in their pain.Investigators determined that patients’ pain “was significantly decreased after the addition of vaporized cannabis.” According to the scientists, medical marijuana “may allow for opioid treatment at lower doses with fewer [patient] side effects.”
“The participants experienced less pain after 5 days of inhaling vaporized cannabis; when the morphine and oxycodone groups were combined, this reduction in pain was significant,” the researchers concluded. “This is the first human study to demonstrate that inhaled cannabis safely augments the analgesic effect of opioids.”
According to the investigators, “These results suggest that further controlled studies of the synergistic interaction between cannabinoids and opioids are warranted.”“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,” Abrams said.
More than 76 million Americans suffer from chronic pain — more than diabetes, heart disease, and cancer combined, according to the National Centers for Health Statistics.
As a cancer doctor, Abrams was motivated to find safer and more effective treatments for chronic pain. Opiates can be highly addictive, and can also be deadly since they can suppress breathing.
Patients in the cannabis-opiates study experienced no major side effects such as nausea, vomiting or loss of appetite.
“What we need to do now is look at pain as the primary endpoint of a larger trial,” Abrams said. “Particularly I would be interested in looking at the effect of different strains of cannabis.”
“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.”