Question:easy
Buprenorphine is which of the following?
Buprenorphine is which of the following?
Show Hint
Think mixed agonist-antagonist with a ceiling on respiratory depression.
Updated On: Jun 24, 2026
- Partial agonist at mu receptor
- Partial agonist at kappa receptor
- Full agonist at mu receptor
- Antagonist at kappa receptor
Show Solution
The Correct Option is A
Solution and Explanation
Buprenorphine belongs to the mixed agonist-antagonist family of opioids. The key to this question is matching one drug to its dominant pharmacodynamic action at each opioid receptor subtype.
At the mu receptor, buprenorphine binds with very high affinity but produces only a sub-maximal response, which is the definition of a partial agonist. This sub-maximal activation explains its analgesic effect together with a ceiling on respiratory depression. At the kappa receptor it behaves as an antagonist, which contributes to fewer dysphoric effects compared with pure kappa agonists.
Because its affinity at mu is so high, it can knock a full agonist such as heroin or morphine off the receptor while delivering only partial signalling, which is why starting it too early can trigger precipitated withdrawal. This same property underlies its usefulness in opioid maintenance therapy, often combined with naloxone to deter misuse.
Running through the choices: full mu agonist describes morphine, not buprenorphine; kappa agonist describes drugs like nalbuphine or pentazocine; and pure kappa antagonism alone does not capture the drug. The single most accurate descriptor is partial mu agonism.
\[\boxed{\text{Partial agonist at mu receptor}}\]
At the mu receptor, buprenorphine binds with very high affinity but produces only a sub-maximal response, which is the definition of a partial agonist. This sub-maximal activation explains its analgesic effect together with a ceiling on respiratory depression. At the kappa receptor it behaves as an antagonist, which contributes to fewer dysphoric effects compared with pure kappa agonists.
Because its affinity at mu is so high, it can knock a full agonist such as heroin or morphine off the receptor while delivering only partial signalling, which is why starting it too early can trigger precipitated withdrawal. This same property underlies its usefulness in opioid maintenance therapy, often combined with naloxone to deter misuse.
Running through the choices: full mu agonist describes morphine, not buprenorphine; kappa agonist describes drugs like nalbuphine or pentazocine; and pure kappa antagonism alone does not capture the drug. The single most accurate descriptor is partial mu agonism.
\[\boxed{\text{Partial agonist at mu receptor}}\]
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