Characterizing withdrawal from long-acting injectable buprenorphine: An observational case series.

Introduction: Long-acting injectable buprenorphine (LAIB) products are being increasingly used to treat patients with opioid dependence. Limited data is available on the severity or timespan (time to onset, peak, duration) of withdrawal signs and symptoms following discontinuation of treatment. Methods: Participants aiming to discontinue long-term LAIB treatment commenced the study on the day of their final dose of Buvidal® 64 mg Monthly. Participants were monitored with weekly assessments of withdrawal severity, cravings, general health, and patient experience measures for up to 16 weeks after last dose. Results: Fifteen participants - those who remained for at least four weeks after the last LAIB dose - were included in the study. There was minimal increase in withdrawal severity over the study period, with an average peak Clinical Opioid Withdrawal Scale score of 4.8 ± 2.7, occurring at a median of 6 weeks (IQR 4-7.5) after the last LAIB dose. Cravings scores were generally low but increased gradually over the 16-week study period. There was no deterioration in physical or mental health scores, and participants reported high levels of satisfaction with the withdrawal experience. Ten participants used rescue medications, predominately in weeks 5 or 6 after the last dose. Discussion and conclusions: Participants (last dose of Buvidal® 64 mg Monthly) experienced minimal or mild withdrawal signs and symptoms, usually peaking in severity between 5 and 8 weeks after the last dose. These results are encouraging, however clinical trials comparing withdrawal outcomes between LAIB, sublingual buprenorphine (SL BPN) and methadone are required to inform treatment planning.