Cannabinoid-Opioid Interaction in Chronic Pain
INVESTIGATOR: DI Abrams, MD
STUDY LOCATION: University of California, San Francisco
PROJECT TITLE: Cannabinoid–Opioid Interaction in Chronic Pain
Cannabis administration significantly augments the analgesic effects of opiates in patients with chronic pain, according to clinical trial data published online in the journal Clinical Pharmacology & Therapeutics.
Investigators at the University of California, San Francisco assessed the use of vaporized cannabis over a five-day period in 21 chronic pain subjects who were on a regimen of twice-daily doses morphine or oxycodone. 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. Subjects' extent of chronic pain was assessed daily.
Researchers determined that subjects' pain "was significantly decreased after the addition of vaporized cannabis" and surmised that cannabis-specific interventions "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. This is the first human study to demonstrate that inhaled cannabis safely augments the analgesic effects of opioids. ... These results suggest that further controlled studies of the synergistic interaction between cannabinoids and opioids are warranted."
Cannabinoids and opioids share several pharmacologic properties and may act synergistically. The potential pharmacokinetics and the safety of the combination in humans are unknown. We therefore undertook a study to answer these questions. Twenty-one individuals with chronic pain, on a regimen of twice-daily doses of sustained-release morphine or oxycodone were enrolled in the study and admitted for a 5-day inpatient stay. Participants were asked to inhale vaporized cannabis in the evening of day 1, three times a day on days 2–4, and in the morning of day 5. Blood sampling was performed at 12-h intervals on days 1 and 5. The extent of chronic pain was also assessed daily. Pharmacokinetic investigations revealed no significant change in the area under the plasma concentration–time curves for either morphine or oxycodone after exposure to cannabis. Pain was significantly decreased (average 27%, 95% confidence interval (CI) 9, 46) after the addition of vaporized cannabis. We therefore 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.
|Journal Article||Clinical Pharmacology & Therapeutics (2011); advance online publication 02 November 2011. doi:10.1038/clpt.2011.188|