Which pharmacotherapies for opioid use disorder are used, and how do they work?

• A. Methadone (full agonist), buprenorphine (partial agonist), and naltrexone (antagonist); stabilize withdrawal, cravings, and reduce mortality.
• B. Methadone is a partial agonist; Buprenorphine is an antagonist; Naltrexone is a full agonist.
• C. Naltrexone only; no effect on withdrawal.
• D. Buprenorphine is a analgesic; Methadone increases cravings.

Answer: (A)

The key idea is that opioid use disorder pharmacotherapies work by targeting the opioid receptors in different ways: replacing opioids to ease withdrawal, partially stimulating receptors to curb withdrawal and cravings safely, or blocking effects to prevent relapse.

Methadone acts as a full mu-opioid receptor agonist, providing steady receptor activation that prevents withdrawal and reduces cravings. Because it’s long-acting, it stabilizes daily function and lowers overdose risk, though it typically requires supervised treatment and careful dosing.

Buprenorphine is a partial mu-opioid receptor agonist with a high receptor affinity and a ceiling on its effects. This means it can relieve withdrawal and cravings with a lower risk of respiratory depression, making it safer and suitable for office-based treatment. It’s often used with naloxone to deter misuse and can precipitate withdrawal if given too soon after a full agonist.

Naltrexone is an antagonist at the mu receptor, blocking the effects of opioids. It’s used after detox to prevent relapse, but it won’t help with withdrawal and can cause withdrawal if opioids are still in the system.

Using methadone, buprenorphine, and naltrexone together reflects the three main pharmacotherapeutic approaches: substitution therapy, a safer partial agonist, and antagonist therapy for relapse prevention. The other statements misstate the drugs’ actions, such as methadone being a partial agonist, buprenorphine being an antagonist, or naltrexone alone addressing withdrawal.