Outpatient Direct Initiation of Injectable Buprenorphine in a Harm Reduction Agency and Primary Care Clinic: A Retrospective Case Series

OBJECTIVES: Initiating weekly long-acting injectable buprenorphine (LAIB) without prior sublingual buprenorphine ("direct-to-inject" or DTI) may reduce buprenorphine initiation barriers. In this case series, we describe outpatient DTI outcomes. METHODS: We conducted a manual chart review of 24 patients undergoing DTI between October 2024 and February 2025 at 3 New York City sites: 2 harm reduction agency-based clinics and a federally qualified health center. Pre- and post-DTI withdrawal data were collected from chart documentation and provider report. Buprenorphine retention was ascertained using electronic medical record medication administration and prescription data and defined as being within the LAIB therapeutic window or having an active sublingual buprenorphine prescription at 30 and 90 days with no gaps greater than 9 or 14 days, respectively. We also measured median buprenorphine treatment days over 90 days post-DTI. RESULTS: Of the 23 patients with available data, 19 (83%) had no withdrawal symptoms pre-DTI. Of the 20 patients with documented post-DTI withdrawal symptoms, 3 (15%) had no withdrawal, 12 (60%) had mild, 4 (20%) had moderate, and one (5%) patient had severe withdrawal. Thirty days post-DTI, 14 (58%) patients were retained on any buprenorphine formulation, and 11 (46%) patients were retained at 90 days. The median post-DTI buprenorphine treatment days were 77 (range: 9-90). CONCLUSIONS: The majority of patients had no pre-DTI withdrawal symptoms, no or mild withdrawal symptoms post-DTI, and were retained on buprenorphine at 30 days post-DTI, with nearly half retained at 90 days. DTI is a promising buprenorphine initiation strategy, but further research is warranted.