Buprenorphine's pharmacological superiority over methadone for opioid use disorder treatment in terms of safety in overdose is explained by which receptor pharmacology concept?

• A Antagonism of kappa-opioid receptors blocking the euphoric effects of co-administered opioids
• B Extended half-life preventing peaks of mu-receptor activation that cause respiratory depression
• C High sublingual bioavailability preventing parenteral misuse and accidental overdose
• D Ceiling effect on mu-opioid receptor-mediated respiratory depression due to partial agonism and limited intrinsic efficacy ✓

Explanation

Buprenorphine is a partial agonist at mu-opioid receptors with high binding affinity but low intrinsic efficacy. As a partial agonist, it exhibits a ceiling effect — beyond a certain dose, increasing buprenorphine does not proportionally increase respiratory depression because maximal receptor activation cannot be achieved. This contrasts with methadone (a full mu-agonist) where dose escalation produces dose-proportional respiratory depression. The partial agonism also means buprenorphine can displace full agonists (competitive binding) while producing less overall signalling, contributing to safety. Kappa antagonism is an additional effect contributing to anti-dysphoria but is not the primary safety mechanism.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.