  The opioid epidemic began with prescription pain relievers. In 2010 Purdue
Pharma reformulated OxyContin to make it more difficult to abuse. OxyContin
misuse fell dramatically, and concurrently heroin deaths began to rise.
Previous research overlooked generic oxycodone and argued that the
reformulation induced OxyContin users to switch directly to heroin. Using a
novel and fine-grained source of all oxycodone sales from 2006-2014, we show
that the reformulation led users to substitute from OxyContin to generic
oxycodone, and the reformulation had no overall impact on opioid or heroin
mortality. In fact, generic oxycodone, instead of OxyContin, was the driving
factor in the transition to heroin. Finally, we show that by omitting generic
oxycodone we recover the results of the literature. These findings highlight
the important role generic oxycodone played in the opioid epidemic and the
limited effectiveness of a partial supply-side intervention.
