Background. Two depot formulations of buprenorphine are publicly funded in Australia for the maintenance treatment of opioid use disorder within a framework of medical, social and psychological treatment. We report retention rates and patient characteristics at three private clinics in Australia where monthly depot buprenorphine injection was available through an early access scheme from January 2019 to February 2020. Methods. Fifty-three patients receiving transmucosal buprenorphine (mean dose 16 mg daily [range 6–32 mg]) transferred to monthly buprenorphine depot. The overall retention rate, and retention rates based on discontinuation defined as a 2- or 4-week treatment delays, were calculated.

Results. Six patients who had planned managed discontinuations from treatment were censored. Four uncensored patients (i.e. expected to continue treatment) missed one depot injection, one missed two, and three discontinued. Kaplan–Meier analysis predicted 67–93% retention at 1 year, depending on the definition of discontinuation. Median time between treatments was 30 days with all definitions. Median retention was not reached in any definition. The patient population (70% male; mean age 39 years; 60% prior heroin users) was consistent with the 2020 National Opioid Pharmacotherapy Statistics Annual Data profile. Most patients were maintained on 100 mg monthly depot; this was not predicted by prior transmucosal buprenorphine dose, age or gender identity. Treatment with this monthly buprenorphine depot supported retention for most patients while allowing flexibility in dosage and dose interval. The small sample and observational design limit predictive power.

Conclusions. Monthly buprenorphine depot promotes long-term treatment for patients in real-world settings.