NDARC’s Kendal Chidwick discusses the findings from a recently published study that examined how patterns of opioid agonist treatment medicines have changed over the past decade.
In Australia, both methadone and buprenorphine have been subsidised by the Pharmaceutical Benefit Scheme (PBS) for the treatment of opioid dependence (termed ‘opioid agonist treatment’ or OAT) for several decades. In September 2019, a new formulation of long-acting injectable buprenorphine became available on the PBS. Administered weekly or monthly, long-acting injectable buprenorphine provides clients with an alternative option to methadone liquid or sublingual buprenorphine tablets, which are otherwise often provided to clients via daily supervised dosing at their local pharmacy or clinic. During the COVID-19 pandemic in 2020, long-acting injectable buprenorphine was recommended as a way for clients to continue on treatment whilst reducing social interactions. Other changes around this time aimed at improving treatment accessibility included increased use of take-home doses and telehealth appointments.
With these recent changes, we wanted to examine trends in opioid agonist treatment medicines over the past ten years. We converted information on monthly sales of methadone, sublingual buprenorphine (+/- naloxone) and buprenorphine between 2013 and 2022 into an estimate of the number of clients receiving these medicines each month, based on average doses in Australia (“client-months”). A chart review of three Australian service providers verified that the long-acting injectable buprenorphine dose estimates used in our study aligned with real-world dosing schedules.
Our recent article, published in the International Journal of Drug Policy, presents the Australia-wide results. Results for each state and territory are available in NDARC Technical Reports**.
- The use of opioid agonist treatment medicines increased steadily between 2013-2022. After adjusting for population size, there was a 33% increase in per-capita client months between January 2013 and December 2022.
- Buprenorphine replaced methadone as the most common opioid agonist medicine. By December 2022, 48% of client months were attributed to methadone, 26% sublingual buprenorphine, and 26% long-acting injectable buprenorphine.
- The introduction of long-acting injectable buprenorphine in September 2019 and policy changes during COVID-19 were associated with a sustained increase in the total number of clients accessing opioid agonist treatment for dependence. Increases were seen for buprenorphine. However, the number of client-months on methadone over the study period remained relatively stable.
- The use of opioid agonist treatment increased in non-community pharmacy settings from early 2020. This increase was particularly evident in drug and alcohol outpatient clinics and prisons. Interestingly, by the end of the study period, 69% of client-months accessed at hospitals were attributed to long-acting injectable buprenorphine and 93% at "other outlets" such as prisons.
- The use of opioid agonist treatment increased in (very) remote areas from early 2020. Rates of OAT use increased across all remoteness categories over the decade, with the most significant increases in very remote areas, from 9 clients per 10,000 capita in January 2013 to 16 per 10,000 capita in December 2022 (+78%).
While both methadone and buprenorphine are first-line options in the treatment of opioid dependence, they differ in terms of some treatment outcomes, including retention and all-cause mortality risk around initiation. So, with these changes to patterns of use in Australia, it will be essential to monitor changes to outcomes at a population level as well as the cost-effectiveness of the program.
* Bharat, C., Chidwick, K., Gisev, N., Farrell, M., Ali, R., & Degenhardt, L. Trends in use of medicines for opioid agonist treatment in Australia, 2013–2022. (2024) International Journal of Drug Policy. Vol 123, p. 104255. DOI: 10.1016/j.drugpo.2023.104255
A copy of the study can be accessed here.
** You can find NDARC's technical reports here: