Introduction Commonly understood as a destructive form of drug use, addiction which in reality is a state of dependence, refers to a compulsive behavior as a result of which an addict is forced to consume a drug of his/her choice in a repetitive manner. This obsession forces the person to procure the substance of choice, consume it until pleasure is diminished with a resulting increase in required dose to achieve the expected level of pleasure (Council of Europe, 2005). Discussion A number of different drug classes are used for addiction purpose; some of them being stimulants, depressants and hallucinogens. As far as the mechanism of action of these drugs is concerned, there is a wide variation between different drug classes; however their effect on the central nervous system appears to be a common phenomenon. There is no consensus among researchers regarding the level of addiction of drugs and due to this reason it is impossible to ascertain with confidence a single drug with the highest level of addiction. However, a number of works have considered Heroin to be heavily catastrophic in terms of its psychoactive effects. Heroin belongs to the class of opiates and other members of this class include agents like morphine, which is a very effective pain-killer and finds widespread use in the field of health care (Goldstein, 2001). Pharmacologically speaking, different types of opioid receptors have been identified in human nervous tissue (Kuhar, 2012). These include the delta, kappa and mu receptors. Their distribution in human body is not limited to the central nervous system (CNS) as their presence has also been detected in peripheral nervous tissue. It is for this reason that the use of opioids not only affects the CNS, but also its peripheral counterpart. Chiefly mediated by the Mu receptor subtype, stimulation of opioid receptors results in the release of dopamine. Dopamine in turn produces the desired pleasant effect. A direct result of repeated use of Heroin is the development of tolerance. As this happens, the body requires elevated doses of the drug to maintain the desired level of euphoria. It is at this point that the drug needs to be taken on repeated basis (Fernandez, 1998). This dependence is perhaps the only factor that drives the multimillion dollar underground drug business throughout the world. The pharmacological impact of Heroin is so profoundly associated with its social implications that the drug is banned worldwide. Massive campaigns were launched in the past to eradicate its cultivation and production; however, success in this regard appears to be limited. In addition to the social issues, there are a number of health issues which arise as a result of Heroin use. These not only make the lives of addicts miserable but also add to the burden of disease in a population. Conclusion Drug addiction is a commonly encountered problem in the modern societies of the world. It is therefore essential to spread awareness among the masses regarding the harmful effects of drug use. Heroin, which was originally used for pain management has turned into an addiction drug with the passage of time. The addictive potential of the Heroin is so high that it cripples the user to an extent where he/she is unable to function normally in the society. Internationally, there have been many efforts to control its spread; however absolute success in this regard seems to be a remote prospect as yet. Perhaps the most effective strategy to control its spread will be to educate the masses regarding the deleterious effects of its use. References Council of Europe. (2005). Biomedical research. Strasbourg. Fernandez, H. (1998). Heroin. Center City, Minn: Hazelden. Goldstein, A. (2001). Addiction: From biology to policy. Oxford: Oxford University Press. Kuhar, M. J. (2012). The addicted brain: Why we abuse drugs, alcohol, and nicotine. Upper Saddle River, N.J: FT Press.