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?