Study of cannabinoid medicine for pain found patients got 'high,' but effects not related to pain relief

Jan 29 2009

Researchers at Brigham and Women's Hospital found that patients taking cannabinoid medicines for pain may be getting "high," but these effects were unrelated to relief from their pain symptoms. Results of their study, one of the first to examine the addictive potential of this class of pain medicine, were presented today at the American Academy of Pain Medicine's 25th Annual Meeting.

In the study, Ajay Wasan, MD MSc and colleagues found that when used for non-cancer pain management, the cannabinoid class of medicines (such as dronabinol), got patients "high," but the majority of subjects experienced significant pain relief independent of these psychoactive effects. Results indicate that these medicines have the likelihood of an addiction similar to smoking marijuana, leading researchers to conclude the abuse potential of this class should be studied further.

Using the Addiction Research Center Inventory (ARCI), the gold-standard for determining the abuse liability of substances, Dr. Wasan and colleagues at McLean Hospital looked at two different patient populations to compare the effects of medicinal, synthetic cannabinoid and marijuana. The first population was suffering from pain, and took each of the following at separate visits where they were observed for eight hours: placebo, 10mg, or 20 mg of dronabinol. The second population was not suffering from pain, but they were monitored every 30 minutes after smoking a high and low strength marijuana cigarette. Participants in both populations were given the ARCI every hour. After two hours, patients in the first population (synthetic cannabinoid medicine) were found to have the same psychoactive effects that patients from the second population (smoked marijuana) did after 30 minutes.

"Based on our study we believe the addictive qualities of this class of medicines need more investigation. In our study, patients taking the medicine, like the patients smoking the marijuana, were, essentially, stoned. However, they didn't report less pain, indicating the pain relief properties were independent of the psychoactive effects," said Dr. Wasan, lead author of the study, and director of clinical pain research at Brigham and Women's Hospital. "We discovered that both the synthetic cannabinoid medicines we studied and marijuana have similar psychoactive properties and suggestive of an addiction potential."