When an attempt is made to move an individual from dependence on one substance to another. In addiction therapy, it usually refers to replacing dependence on a dangerous drugA name for a wide variety of chemical substances capable of altering the function of your mind and body in significant ways. These can include over the counter prescriptions, alcohol, and controlled substances. Most drugs are either physically and/or psychologically habit-forming. More such as heroinAn opioid used as a recreational drug that is often injected. It has a euphoric effect on the user and is highly addictive both psychologically and physically. It is known for being one of the primary drugs involved in opioid overdoses and for its particularly nasty withdrawal symptoms. More with a less harmful substitute such as methadoneA relatively weak and long-lasting opiate. Due to these characteristics, it is used for opioid maintenance therapy, usually as a replacement for heroin. It can also be used for chronic pain management. More.