Buprenorphine is used for opioid use disorder. Its 'ceiling effect' for respiratory depression but efficacy as an analgesic/substitution therapy is explained by its pharmacological profile as:

• A Partial agonist at mu-opioid receptors and antagonist at kappa and delta receptors ✓
• B Full agonist at mu-opioid receptors with partial agonism at kappa receptors
• C Full antagonist at all opioid receptors with mixed action on nociceptin receptors
• D Partial agonist at kappa receptors only, with no mu receptor activity

Explanation

Buprenorphine is a partial agonist at mu-opioid receptors (high affinity, low intrinsic efficacy) and an antagonist at kappa and delta receptors; as a partial mu agonist its dose-response curve plateaus (ceiling effect) for respiratory depression but provides sufficient analgesia and reduces withdrawal symptoms. Its very high mu receptor affinity (Kd ~0.2 nM) means it displaces full agonists and can precipitate withdrawal in dependent patients. The kappa antagonism prevents dysphoric side effects.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.