A UCSF study suggests patients with chronic pain may experience greater relief if their doctors add cannabinoids - the main ingredient in cannabis or medical marijuana - to an opiates-only treatment. The findings, from a small-scale study, also suggest that a combined therapy could result in reduced opiate dosages.
More than 76 million Americans suffer from chronic pain - more people than diabetes, heart disease and cancer combined, according to the National Centers for Health Statistics.
"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, professor of clinical medicine at UCSF and chief of the Hematology-Oncology Division at San Francisco General Hospital and Trauma Center (SFGH). "And chronic pain is, unfortunately, one of the problems we're least capable of managing effectively."
In a paper published this month in Clinical Pharmacology & Therapeutics, researchers examined the interaction between cannabinoids 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.
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 focus was on whether the opiates' effectiveness increased, not on whether the cannabinoids helped reduce pain.
"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."
Abrams and his colleagues studied 21 chronic pain patients in the inpatient Clinical & Transitional Science Institute's Clinical Research Center at SFGH: 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 four consecutive days. On the fifth day, they looked again at 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," Abrams said. "So that was a little surprising."