Treatment heroin addicts with methadone is more properly referred to as the:

the answer is maintenance model
maintenance model refers to the model that focused on influencing the patient's perception and self-evaluation.
 methadone Prevents the Euphoric rush that addicts often felt toward certain drugs, which make them perceive that they don't need the drug as much as they previously believed.

The treatment is called Opioid Replacement Therapy (ORT). This is the treatment of heroine, which in most cases causes physical dependence to the drug, that could help with it's longer acting effect but with lesser euphoric opioid. Another common drug used in this treatment is Burprenophine.