In states where medical marijuana laws are passed, did prescription painkiller sales decrease?

Question

I recently heard that US states where medical marijuana laws are passed have seen a decrease in prescription painkillers sales.

For the study, researchers analyzed all deaths caused by opioid overdoses between 1999 and 2010 in the U.S. Then, they determined the association between medical cannabis laws and opioid analgesic-related deaths using linear time-series regression models. The various models helped the researchers determine that in every state that legalized medical marijuana between the aforementioned years (a total of 13 states), there was a 25% reduction in deaths related to the overdose of legally prescribed painkillers.

It seems that because of the lower prescription painkiller sales, the large pharmaceutical companies are leading the way to stop the legalization of it in additional states. This seems reasonable, but I don't think pharmaceutical companies release their sales figures by state. Is this true and is there any evidence to support it?

Answer 1

Yes, this was studied in Medical Marijuana Laws Reduce Prescription Medication Use In Medicare Part D Health Affairs July 2016 vol. 35 pages 1230-1236 :

In states with medical marijuana laws, pain medication was reduced by 1,826 daily doses filled per physician per year.

Ultimately, we estimated that nationally the Medicare program and its enrollees spent around $165.2 million less in 2013 as a result of changed prescribing behaviors induced by seventeen states and the District of Columbia—the jurisdictions that had legalized medical marijuana by then.