We study how pharmacy competition affects the most severe realizations of the opioid epidemic: overdose deaths. We propose a novel, data-driven market definition where each pharmacy sits at the center of its own market defined by the travel behavior of its customers. We find that a one standard deviation increase in market concentration (HHI) is associated with a 15.5 percent decline in opioid mortality. Our results suggest that greater competition may exacerbate risky dispensing. We also show that PDMP effects vary across markets, implying a “one size does not fit all” policy environment.
Diaz-Campo, Cecilia Silvina and Bradford, W. David, Pharmacy Market Structure and the Opioid Epidemic (June 18, 2025). http://dx.doi.org/10.2139/ssrn.5310323
