The Pharmacology of Buprenorphine Microinduction for Opioid Use Disorder.

Although expanding the availability of buprenorphine-a first-line pharmacotherapy for opioid-use disorder (OUD)-has increased the capacity of healthcare systems to offer treatment, starting this medication is fraught with significant barriers. Standard induction regimens require persons with OUD to taper and discontinue full opioid agonists and experience opioid withdrawal prior to the first dose of buprenorphine. Further, emerging evidence indicates that precipitated withdrawal during induction may impact long-term treatment outcomes. Microinduction is a novel approach that, by harnessing buprenorphine's unique pharmacological profile, may allow circumventing the needed for prolonged opioid tapers, and reduce the risk of precipitated withdrawal-holding promise to enhance treatment access. In this review, we examine the pharmacological basis for microinduction and appraise the evidence of this approach to improve clinical outcomes among persons with OUD. First, we highlight the potential dose-dependent effects of buprenorphine on two key neuroadaptations at the mu-opioid receptor (MOR)-resensitization and upregulation. We then focus on how microinduction may reverse these chronic MOR neuroadaptations, allowing the maintenance of an adequate opioid tone, and thereby potentially circumventing opioid withdrawal. Second, we describe the clinical evidence available, derived from observational reports and open-label studies, examining the potential efficacy of microinduction. Despite significant heterogeneity-exemplified by variable buprenorphine formulations, daily doses, and schedules of administration-these data provide preliminary support for the feasibility of microinduction. Finally, we provide new mechanistic, methodological, and clinical insights to guide future translational research, as well as randomized, placebo-controlled clinical trials in this compelling agenda of pharmacotherapy development.