Which statement correctly contrasts methadone and buprenorphine?

Which statement correctly contrasts methadone and buprenorphine?

• A. Methadone is a long acting mu receptor agonist; buprenorphine is shorter acting partial agonist with lower overdose risk
• B. Methadone is a short acting antagonist; buprenorphine is long acting full agonist
• C. Methadone and buprenorphine have identical half-lives and overdose risks
• D. Buprenorphine has no ceiling effect

Answer: (A)

Attributed actions at the mu opioid receptor explain the contrast. Methadone is a long-acting full mu receptor agonist, so it continually activates mu receptors and can produce strong opioid effects, with a real risk that higher doses lead to dangerous respiratory depression. Buprenorphine, by contrast, is a partial mu receptor agonist with very high receptor affinity, so its maximal effect is limited. That creates a ceiling for respiratory depression and overdose risk, making it safer in overdoses compared with methadone. In practice, buprenorphine’s safety comes from this ceiling effect, even though both drugs can have long durations. It’s also important to note that buprenorphine can precipitate withdrawal if given to someone currently dependent on full agonists, due to its high affinity and partial agonism.

Attributed actions at the mu opioid receptor explain the contrast. Methadone is a long-acting full mu receptor agonist, so it continually activates mu receptors and can produce strong opioid effects, with a real risk that higher doses lead to dangerous respiratory depression. Buprenorphine, by contrast, is a partial mu receptor agonist with very high receptor affinity, so its maximal effect is limited. That creates a ceiling for respiratory depression and overdose risk, making it safer in overdoses compared with methadone. In practice, buprenorphine’s safety comes from this ceiling effect, even though both drugs can have long durations. It’s also important to note that buprenorphine can precipitate withdrawal if given to someone currently dependent on full agonists, due to its high affinity and partial agonism.