# Extended-release Injectable Buprenorphine Initiation in the Emergency Department

## TL;DR

This study shows that starting extended-release buprenorphine in the emergency department leads to high treatment retention for opioid use disorder.

## Contribution

The study introduces a novel ED-based pathway for initiating extended-release buprenorphine and demonstrates its effectiveness in retaining patients.

## Key findings

- 73.9% of patients who received XR-BUP in the ED returned for a second injection.
- 69.6% of ED XR-BUP administrations were due to instability in OUD treatment.
- Patients with co-occurring substance use disorders were more likely to return for follow-up treatment.

## Abstract

Extended-release buprenorphine (XR-BUP) is a long-acting injectable medication used for the treatment of opioid use disorder (OUD). It is currently approved for use in patients who have been administered at least seven days of sublingual buprenorphine (SL-BUP). For patients with OUD who are unstable (ie, not at treatment goal, with active opioid use) or not yet on medication for OUD (MOUD) such as SL-BUP, the emergency department (ED) setting is an essential location for access to treatment. There is, as yet, no research on the utility of on-demand XR-BUP administration in the ED.

We performed a retrospective cohort study of individuals with OUD who received XR-BUP in the ED through our novel reallocation pathway. We reviewed charts from an addiction medicine specialty outpatient clinic to determine retention in treatment, continuation on XR-BUP, and reported quantitative analysis. Our primary outcome was retention in treatment, measured by subsequent XR-BUP injection after initial ED XR-BUP administration. The secondary outcome was the reason for ED administration of XR-BUP (as opposed to administration in the clinic setting).

Our study population included 69 patients (68.2% male). Our primary outcome showed that 51 (73.9%) patients who had their first injection in the ED received a second XR-BUP injection and 40 (58%) received their third XR-BUP injection. Our secondary outcome showed that 7.2% had barriers with access to treatment; however, most of the patients received the injection due to instability of the treatment of the OUD (69.6%). These patients were either unable to adhere to MOUD, reported issues with the prescription, or were still using substances while on MOUD. For 52 (75%) patients, the index ED injection was their first ever XR-BUP injection. Logistical regression analyses demonstrated that clinical and demographic factors did not lead to increased attrition, while patients with other co-occurring substance use disorders were more likely to present for follow-up treatment.

In our retrospective study, patients who received ED-initiated extended-release buprenorphine had a strong retention rate compared to previous studies evaluating ED-initiated sublingual BUP (retention rates ranging from 16.7–60%). The ED provided a convenient healthcare access point for XR-BUP initiation. The XR-BUP is a helpful tool for achieving induction after failed SL-BUP initiation and may have further implications in minimizing treatment gaps after discharge and improving OUD treatment retention.