Buprenorphine is used for opioid use disorder maintenance therapy. Its pharmacological profile that makes it safer than full agonists (e.g., methadone) in terms of respiratory depression is:

• A It is a μ-receptor antagonist and κ-receptor partial agonist with ceiling effect at all opioid receptors
• B It is a partial μ-opioid receptor agonist with a ceiling effect for respiratory depression (but not analgesia), and very high μ-receptor affinity preventing displacement by illicit opioids ✓
• C It activates δ-opioid receptors, which do not mediate respiratory depression
• D It has very low bioavailability limiting systemic opioid effects

Explanation

Buprenorphine is a partial μ-receptor agonist (and κ-antagonist) with intrinsic efficacy lower than full agonists. Its dose-response curve for respiratory depression reaches a plateau (ceiling effect) at lower doses than analgesia, giving a wider therapeutic window and reduced overdose risk compared with full agonists like methadone or oxycodone. Its extremely high μ-receptor affinity (Kd in picomolar range) means it is not easily displaced by other opioids, stabilising patients against the euphoric effects of illicit opioid use. In combination with naloxone (Suboxone), diversion for IV misuse is reduced.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.