Responding to an opioid crisis in Canada, policy makers have implemented supply-side interventions seldom used in the US, regulating insurance reimbursement to discourage the prescribing of specified opioids. Using national databases of all opioids dispensed through provincial pharmaceutical programs and of opioid hospitalizations from January 2006 through March 2017, we found that requiring physicians to obtain prior authorization for patients to receive reimbursement for OxyContin prescriptions substantially reduced OxyContin fills, particularly among opioid-naive patients; it also reduced overall opioid prescriptions, suggesting limited substitution. "Grandfathering" OxyNeo (an abuse-resistant OxyContin variant), allowing previous OxyContin patients to obtain OxyNeo, increased OxyNeo fills but had no detectable effect on total opioid prescriptions, which points to substantial opioid substitution among chronic users of prescription opioids. We found no effects of regulatory changes on opioid-related hospitalizations. These results suggest that restrictions on pharmaceutical formularies can reduce fills of targeted opioids with the additional benefit of altering treatment of opioid-naive and other patients differently. Canadian policy makers may wish to extend such regulations to more provincial formularies and private insurers, and policy makers in the US and elsewhere could fruitfully follow suit.
Keywords: Drug use; Formularies; Global health; Health policy; Insurance market regulation; Mortality; Opioid use disorder; Patient harm; Pharmaceuticals; Prescription drugs; Regulation.