Impact of policy changes and drug shortages on acamprosate and naltrexone use in Ontario, Canada

Background — Acamprosate and naltrexone, evidence-based pharmacotherapies for alcohol use disorder (AUD), are publicly covered by the Ontario Drug Benefit (ODB) programs; however, their availability has changed over time, with expanded formulary access in July 2018, followed by an acamprosate shortage in February 2019 and ending in July 2020. We evaluated the impact of these events on the use of these medications in Ontario, Canada.

Methods — We conducted a time-series analysis among individuals with AUD dispensed acamprosate or naltrexone through the ODB from July 2016 to December 2020. Outcomes included monthly rates of those with AUD on therapy (primary), and rate of initiation (secondary) overall and by treatment type. We used autoregressive moving average models to evaluate the impact of expanded coverage and the acamprosate shortage on rates of use, and reported characteristics at first dispensation.

Results — Over the study period, 10,637 individuals (61.0% male) initiated acamprosate or naltrexone. Expanded coverage increased monthly utilization rates of acamprosate (p=0.0004), naltrexone (p<0.0001), and either AUD pharmacotherapy (p<0.0001). The acamprosate shortage led to a 98.1% reduction in acamprosate use (p=0.0003) but did not impact naltrexone (p=0.51). Our secondary analysis yielded consistent results with respect to the shortage; however, the expanded formulary listing did not impact the rate of new acamprosate patients (p=0.3). By December 2020, 5.3% of ODB recipients with AUD were accessing pharmacotherapy.

Conclusions — Although coverage expansion increased access to medications that treat AUD, the shortage of acamprosate led to large reductions in its use, with no responsive increase in naltrexone prescribing.