True or False: Methadone lasts longer than Buprenorphine?

• A. True
• B. False
• C. It depends on dose
• D. It depends on route of administration

Answer: (B)

Duration of opioid effects depends not just on how long the drug stays in the body, but on how it interacts with receptors. Buprenorphine binds mu-opioid receptors very tightly and dissociates slowly, so once it occupies those receptors, its effects can persist for a long time. Methadone is also long-acting, but it does not bind as tightly or dissociate as slowly as buprenorphine. As a result, buprenorphine can have a longer duration of action in many situations, making the statement false. Note that actual duration can vary with dose, tolerance, and other factors, but the key idea is buprenorphine’s high receptor affinity and slow dissociation give it prolonged effects compared to methadone.