A partial agonist meaning it activates the opioid receptors in the brain, but to a much lesser degree than a full agonist. Buprenorphine also acts as an antagonist, meaning it blocks other opioids, while still allowing for some opioid effect of its own to suppress withdrawal symptoms and cravings. This is why it would be misleading to classify buprenorphine as a replacement therapy. It would be equally misleading to classify it solely as an opioid blocker. Buprenorphine is in a category of its own, and therefore should not be seen as “replacement” or “substitution” for anything else.”