Buprenorphine is used for opioid use disorder maintenance therapy. Its ceiling effect on respiratory depression is attributed to:

• A Being a pure mu-opioid receptor antagonist with no intrinsic respiratory effects
• B Being a kappa receptor agonist that counteracts mu-mediated respiratory depression
• C Being a partial agonist at mu receptors — at higher doses, increasing receptor occupancy does not proportionally increase receptor activation, producing a plateau in maximal efficacy ✓
• D Having high affinity for mu receptors but rapid dissociation kinetics, preventing sustained respiratory depression

Explanation

Buprenorphine is a high-affinity partial agonist (partial efficacy) at mu-opioid receptors. As a partial agonist, it activates receptors with lower intrinsic efficacy than full agonists even at maximal receptor occupancy; this produces a ceiling effect on respiratory depression beyond which additional doses do not produce proportionally greater depression. This property, combined with its very high receptor affinity and prolonged duration of action, makes buprenorphine safer in overdose and effective for maintenance therapy — it also blocks full agonist binding.

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

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Written and medically reviewed by the StethoPrep medical team.