Buprenorphine is used for opioid dependence maintenance therapy. Its 'ceiling effect' on respiratory depression while retaining analgesic efficacy is explained by its pharmacology as:

• A A full μ-opioid agonist with rapid receptor dissociation
• B A κ-opioid full agonist that does not cause respiratory depression via κ-receptor pathways
• C A partial μ-opioid agonist with very high receptor affinity and slow dissociation, producing submaximal respiratory depression even at high doses ✓
• D An opioid antagonist at μ-receptors that paradoxically produces analgesia via δ-receptor activation

Explanation

Buprenorphine is a partial agonist at μ-opioid receptors with very high receptor affinity (Kd in the picomolar range) and extremely slow receptor dissociation (high receptor residence time). As a partial agonist, it has an intrinsic ceiling on μ-mediated effects including respiratory depression, even as doses increase beyond a threshold. The high affinity means it displaces full agonists from μ-receptors and can precipitate withdrawal if given to opioid-dependent patients. Its high receptor affinity also means standard naloxone doses may not fully reverse it, requiring higher or repeated doses.

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

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Written and medically reviewed by the StethoPrep medical team.