Opioids have been used for thousands of years, and it has long been known that many people who have become dependent on opioids have extreme difficulties permanently ending their use of them. Suffering through the withdrawal sickness is only part of the problem. The real difficulty has always been staying off the drugs once the period of withdrawal is over.
Just as in the case of those who are unable to stop smoking, it is difficult to explain why it is so hard not to return to the use of opioids. Reasons include long-term depression, lack of energy, drug cravings, and sudden attacks of physical withdrawal sickness. Some people find these problems diminish over time and eventually disappears altogether- but others continue to suffer these symptoms indefinitely, and many of them eventually relapse to their regular use of opioids.
The reason that people relapse often has nothing to do with lack of power or other personal problems. Instead, it appears that people with a long history of opioid problems have experienced changes to the part of their brains that allow a person to feel and function normally. This part of the brain makes and uses its own natural opioids.
The best known opioids are the chemicals known as endorphins. The word endorphin literally means "the morphine within." Indeed, these chemicals are functionally identical to morphine or heroin.
We don't yet understand everything that these natural opioids do in the body, but evidence suggests that they are involved with pain control, learning, regulating body temperature, and many other functions.
It is possible that people who develop a dependency on opioids were born with an endorphin system that makes them particularly vulnerable. For example, we know that addiction appears to run in some families.
Addiction might also be related to changes in the brain caused by the overuse of heroin or other opioids. Or, it may be the result of a complex relationship between genetics and the environment.
We do not yet know exactly how this malfunctioning occurs, or even whether all people who feel unable to stop using opioids have this damage. There is, however, an increasing amount of evidence that many people who find it difficult to end their use of opioids have experienced these physical changes- which are likely to be permanent.
There is not yet any test that can determine how much damage a person may have to his or her natural opioid system, or how hard it may be for that person to stay away from opioids. All that we know for sure right now is that relapse is a major feature of opioid dependency.
Methadone and Buprenorphine/Suboxone are not cures for the problem of opioid dependency. They are treatments - which are effective for only as long as a person continues to take appropriately.