Buprenorphine Pharmacology Review: Update on Transmucosal and Long-acting Formulations

Abstract

: Buprenorphine is an effective treatment for opioid use disorder. As a high-affinity, partial agonist for the mu-opioid receptor, buprenorphine suppresses opioid withdrawal and craving, reduces illicit opioid use, and blocks exogenous opioid effects including respiratory depression. Other pharmacologic benefits of buprenorphine are its superior safety profile compared with full opioid agonists and its long half-life that allows daily or less-than-daily dosing. New and innovative buprenorphine formulations, with pharmacokinetic profiles that differ from the original tablet formulation, continue to be developed. These include higher bioavailability transmucosal tablets and films and also 6-month implantable and monthly injectable products. This growing array of available formulations allows more choices for patients and increased opportunity for clinicians to individualize treatment; thus, it is important for buprenorphine prescribers to understand these differences.

Figure 1.

Dose-response curve schematic of three opioid agonists. At a low dose (Dose A), fentanyl and buprenorphine produce significantly greater responses than morphine (i.e., fentanyl and buprenorphine are more potent than morphine). While fentanyl response is dose-related until reaching 100% maximal response, buprenorphine effects reach a ceiling, at which point further increases in dose do not increase the magnitude of response. Because buprenorphine is a partial agonist, it cannot not produce a 100% response like a full agonist (i.e., fentanyl) can. At higher doses (Dose B), morphine (a full agonist with low potency) produces greater response than buprenorphine.