Hi Zhao Wei, Your desire is vague. If you want the meaning of the given word I have to say that it's a drug that is often given to people who are trying to stop taking heroin. But if you want a synonym for it you can use "synthetic heroin" which is a drug similar to morphine but less habit-forming; used in narcotic detoxification and maintenance of heroin addiction.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.