Alcohol use disorder (AUD) is an ongoing public health issue in Canada, affecting 1 in 5 Canadians in their lifetime (Taillieu et al., 2020). If untreated, AUD can have physical, mental, social, and economic consequences (Collins, 2016; Helzer and Pryzbeck, 1991). AUD treatment options in Canada include counselling, support programs, and pharmacotherapy (Spithoff et al., 2017). As first-line anti-craving agents, acamprosate and naltrexone were approved by Health Canada in 2007 and 1997, respectively (Richardson et al., 2008). Acamprosate is indicated for patients with a goal of abstinence from alcohol, while naltrexone is used in patients with either a goal of abstinence or reduction in drinking (British Columbia Centre for Substance Use, 2019).

Both medications are currently covered by the public drug plan in Ontario; yet prior to 2018, accessing these medications required prior authorization, where physicians were required to send a formal request on behalf of their patients to the Ontario Ministry of Health and Long-term Care. Eligibility requirements for naltrexone included an AUD diagnosis and counselling. In order to be eligible for acamprosate, patients needed to fail previous treatment or have a contraindication to naltrexone, and be abstinent from alcohol for at least 4 days (Maisel et al., 2013; Spithoff et al., 2017). On June 29, 2018 public drug coverage expanded to be more inclusive and removed the administrative burden on physicians when prescribing these medications. This included the removal of prior authorization requirements, and listing these medications with ‘limited use’ criteria only required patients to express a willingness to abstain from alcohol, participate in counselling, and desire treatment (Queen’s Printer for Ontario, 2021, Queen’s Printer for Ontario, 2019). Under limited use requirements, physicians simply indicate that their patient meets these criteria. However, following this broadened access, on January 29, 2019, Canada experienced an acamprosate shortage that lasted until June 2020, and likely impacted access to acamprosate across the country (Drug Shortages Canada, 2020). Despite this, little is known about how changing availability and accessibility to medications for AUD through public drug programs impacted population-based rates of use. Therefore, we aimed to examine the impacts of expanded public drug coverage in 2018, and the subsequent acamprosate drug shortage in 2019 on utilization rates of these medications across Ontario, Canada.