Medical cannabis laws (MCLs) are associated with significant reductions in opioid prescribing in the Medicare D population, a recent study found. The longitudinal analysis examined the daily doses of opioids filled in Medicare Park D for all opioids as a group and for categories of opioids by state and state-level MCLs from 2010 through 2015. The primary outcome was the total number of daily doses prescribed in each US state for all opioids. The secondary analysis examined the association between MCLs separately by opioid class. Researchers found:

• Prescriptions filled for all opioids decreased by 2.11 million daily doses per year from an average of 23.08 million daily doses per year when a state instituted any medical cannabis law.
• Prescriptions for all opioids decreased by 3.742 million daily doses per year when medical cannabis dispensaries opened.
• Results varied by type of opioid, with statistically significant estimated negative associations observed for hydrocodone and morphine.