Study: Prescription Opioid Distribution Falls Following Adult-Use Marijuana Legalization

Thursday, 21 May 2020

Scranton, PA: The enactment of adult-use marijuana legalization in Colorado is associated with a significant reduction in prescription opioid distribution, according to data published in the International Journal of Environmental Research and Public Health.

A team of researchers affiliated with the Geisinger Commonwealth School of Medicine in Pennsylvania and the University of New England in Maine examined opioid distribution trends in Colorado following legalization as compared to trends in two control states, Utah and Maryland. (Maryland legalized medical cannabis dispensing in 2014.) Investigators assessed dispensing trends for nine prescription opioids used for pain (e.g., fentanyl, morphine, hydrocodone, hydromorphone, and oxycodone) as well as for methadone and buprenorphine, which are primarily prescribed to treat opioid use disorder (OUD).

Authors reported a greater than 30 percent reduction in opioid dispensing in Colorado between 2007 and 2017. That reduction was significantly larger than what was observed in the control states over the same period of time. However, because the study design was observational in nature, authors could not determine whether legalization was independently responsible for the change.

Researchers concluded: "In this study, we observed dynamic changes in opioid distribution for eleven opioids used for pain and OUD within Colorado, and two carefully selected comparison states, Utah and Maryland, from 2007 to 2017. Colorado, after legalizing recreational marijuana, had a significant decrease in prescription opioids distributed for pain. The findings from this geographically limited study were challenging to interpret because, while analgesic opioid use was unchanged in Utah, Maryland also had a significant decline [though this decline was not as significant as was observed in Colorado.] Other national research more clearly showed that marijuana policies were associated with reductions in analgesic opioid use. This appears to be an empirically informed public policy strategy which may contribute to reversing the US opioid epidemic."

The study's findings are consistent with those of a number of prior observational studies as well as with numerous longitudinal studies reporting that pain patients typically reduce their use of prescription opioids after enrolling in state sanctioned medical cannabis access programs.

Full text of the study, "Prescription opioid distribution after the legalization of recreational marijuana in Colorado," appears in International Journal of Environmental Research and Public Health. Additional information appears in the NORML, "Relationship Between Marijuana and Opioids."