How do methadone clinics help with addiction?

Methadone is a narcotic drug used to treat chronic pain and opiate addiction from drugs such as opium or heroin. The drug was originally developed in Germany, during World War II, and then introduced to the United States in 1947, and originally used as a long-acting painkiller, and it wasn't until 1950 that it was found to be effective in treating the withdrawal of a opiate and heroin addict. Methadone helps with the addiction of opiates and heroin because it fits into the same receptors as opiates and can relieve many of the symptoms of opiate withdrawal. The difference between methadone and opiates is that methadone does not cause that euphoric high and can actually block the effects of opiate drugs by preventing someone from getting high on opiates or heroin when they relapse. Methadone is not a cure for opiate addiction and is actually addictive, in and of itself. So methodone clinics do not cure the addiction but rather help addicts start on the road to addiction by taking away the negative withdrawal.

http://www.livestrong.com/article/29470-methadone-treatment-work/