Buprenorphine is used in opioid use disorder because it prevents withdrawal while blocking heroin's euphoric effects. The pharmacological property enabling this unique clinical profile is:

• A Full agonist at kappa receptors and full antagonist at mu receptors
• B Delta receptor agonism compensating for mu receptor blockade
• C Non-competitive mu receptor antagonism with irreversible binding
• D Partial agonist at mu receptors with very high receptor affinity and slow dissociation (ceiling effect) ✓

Explanation

Buprenorphine has extremely high affinity for mu-opioid receptors (Ki ~0.2 nM, higher than most full agonists) but is a partial agonist with low intrinsic efficacy. This creates a 'ceiling effect' — above a certain dose, increasing buprenorphine does not produce greater respiratory depression or euphoria. Its high affinity also means it displaces full agonists (like heroin/morphine) from receptors, blocking their euphoric effects. Slow receptor dissociation (t½ binding ~25 hours) enables once-daily dosing.

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

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Written and medically reviewed by the StethoPrep medical team.