Utilization of Opioid Agonist Therapies in Canada
Authors: Mendell Ari , Vannabouathong Chris , Le Kim , Dyrda Peter 
Published: August 2023

Canada continues to experience an opioid crisis that has had a devastating impact on public health, highlighting the importance of management strategies for opioid use disorder (OUD). Several opioid agonist therapies (OATs) for the management of OUD are available in Canada, including recent approvals of new brand name drugs and generic versions of widely used OATs.
Coverage criteria for OATs are comparable across public drug plans in Canada. Methadone hydrochloride (HCL) and the combination of buprenorphine HCL and naloxone HCL (buprenorphine HCL-naloxone HCL) are typically listed as regular or open benefits; generics for these 2 medications have been available since 2020 and 2013, respectively. Sublocade and Probuphine — long-acting buprenorphine preparations approved by Health Canada in 2018 — have varied coverage that is often dependent on prior therapy requirement.
The annual number of public claims for OATs decreased by 19.5% from 2018 to 2022. The market share of claims during this period was dominated by methadone HCL and buprenorphine HCL-naloxone HCL, with an increase in claims market share for buprenorphine over time (starting in 2020) and a negligible contribution by buprenorphine HCL. Additionally, in a subanalysis on the number of OAT claimants, the results did not indicate a decrease in individual beneficiaries for these medications; therefore, the decrease in OAT claims was likely driven by increased usage of OATs that require fewer claims per patient, as opposed to decreased OAT use in the population.
Despite the decrease in annual OAT claims during the analysis period, total OAT expenditures increased every year, with a 67.0% increase from 2018 to 2022 (5-year total of $307 million). The increase was initially driven by buprenorphine HCL-naloxone HCL, which increased from $27 million (58.9% of OAT expenditures) in 2018 to $39 million (67.2% of OAT expenditures) in 2019. Thereafter, expenditures for buprenorphine drove overall OAT cost increases from 2020 onward, accounting for $22 million (28.2% of OAT expenditures) in 2022. In contrast, methadone HCL accounted for a decreasing proportion of expenditures each year ($19 million or 41.1% of OAT expenditures in 2018 to $16 million or 21.0% of OAT expenditures in 2022), despite having the greatest proportion of claims throughout the study period.
The availability of new OAT formulations and generic versions of existing products, as well as other notable regulatory policy changes (e.g., Health Canada’s removal of the need for an exemption to prescribe methadone HCL) and reimbursement decisions (e.g., positive reimbursement recommendations from CADTH for the newer branded OATs, Sublocade and Probuphine), impacted the observed utilization and expenditure patterns, and will likely continue to influence decision-making, particularly where coverage has recently changed or has yet to change to reflect the evolving landscape. If the utilization of injectable buprenorphine (Sublocade) continues at the rate observed in this analysis, it will likely continue to drive increases in OAT expenditures; Sublocade has several patents and the earliest patent expiry is not until 2031, so generic versions of this formulation will likely not be available for several more years. Overall, the findings of this analysis may help to inform jurisdictions in funding decisions regarding OATs for the treatment of OUD.