Introduction â Heroin Addiction
Heroin addiction is a significant health and social problem in most countries. A recent estimate is that there were between 15.2-21.1 million people abusing or dependent on opioids. The key determinant of the prevalence of heroin problems in a community appears to be availability. The highest levels of use (in terms of the proportion of the population aged 15-64 years) are found along the main drug trafficking routes out of Afghanistan (1), and more than half of the worldâs opioid-using population are thought to live in Asia.
Use of heroin is associated with a range of harms. The injecting of street drugs, and sharing of needles is a major route of transmission of blood-borne viruses (BBV), notably Hepatitis C and HIV. Age-adjusted mortality among heroin users is high, 1â3% per annum (2,3). Among younger heroin users, overdose is the most common cause of death, with suicide and violence also contributing to mortality (4). As addicts and former addicts age, deaths due to liver disease, AIDS, and a variety of medical conditions, become more common (5).
Heroin use is strongly associated with social disadvantage, psychological problems and deviant behaviour (6). International studies suggest that for opioid dependent persons in the criminal justice system, and those seeking treatment, addiction is a chronic, relapsing and remitting condition (7) with a high risk of relapse even after periods of abstinence.
Opioids have a range of physiological effects, but the critical issue which make opioids reinforcing is that, like most drugs of misuse, they act on a region of the brain dubbed the âreward pathwayâ. Drugs which stimulate dopamine release in this pathway â such as alcohol and nicotine, as well as opioids - produce reduction in anxiety, and a sense of well-being and confidence. These reinforcing effects explain the appeal of recreational drugs. With repeated, especially continuous, exposure, higher doses are required to achieve the same subjective effects (tolerance), and with prolonged exposure, a withdrawal syndrome develops on stopping the drug. It is hypothesized that the chronic administration of opioids (and other drugs) produces enduring changes in brain neurotransmitter systems that leave the user vulnerable to relapse after abstinence has been achieved (8).
Opioid Substitution Treatment of Heroin
Use of drugs may initially be motivated by novelty seeking or pursuit of euphoria, but once dependence is established, drug use is primarily maintained by the need to avoid withdrawal. Drug free treatment is based on interrupting drug use long-enough for the acute withdrawal reaction to subside, and providing lasting support to remain abstinent. Opioid Substitution Treatment (OST) involves prescribing opioids (methadone, buprenorphine, and in some jurisdictions other agents) to patients who are opioid dependent. The importance of suppressing withd