What is the mechanism of action of Methadone?

Methadone functions primarily as a full opioid agonist, which means it binds to and activates opioid receptors in the brain, particularly the mu-opioid receptors. This binding leads to pain relief and a sense of euphoria, similar to other opioids, which can help manage withdrawal symptoms in individuals recovering from opioid use disorder.

Unlike partial agonists, which only partially activate the receptor and therefore have a ceiling effect, methadone fully activates the opioid receptors, allowing it to provide robust analgesia and contribute to the stabilization of patients in medication-assisted treatment. This mechanism is vital for mitigating cravings and preventing relapse in individuals undergoing recovery, while also providing sufficient control over withdrawal symptoms.

The other answer choices do not accurately represent methadone's pharmacological profile, which is why they are considered less relevant to its primary role in treatment settings.