The "Clinical Textbook of Addictive Disorders" says that opiate drugs are natural or synthetic derivatives of the opium poppy. They include such drugs as heroin, morphine, codeine, oxycodone and methadone. According to the text "Essential Psychopharmacology," opiates are pain-relievers that also induce a sense of euphoria; this property makes taking opiates a rewarding experience for the brain. Some opiates induce a profound and intense sensation of euphoria called a "rush" that is followed by a period of peaceful tranquility. There are many causes that contribute to opiate addiction.
Reinforcement
The text "Drug and Alcohol Abuse" explains that drug abuse and addiction is mediated in part by positive reinforcement in a part of the brain called the limbic system. When a user takes an opiate drug and experiences euphoria and pain relief, the brain interprets the experience as enjoyable. When the effects of the drug wear off, the user is once again driven to seek out the drug that provided the pleasant feelings, or reward.
Drug Tolerance
The "Clinical Textbook of Addictive Disorders" explains that as the body grows accustomed to the presence of opiates, the cells in the body will make changes in order to function as they normally would despite the presence of the drug. This will lead to the user requiring higher doses of the drug in order to experience the euphoric and pain-relieving effects. With continued abuse of opiate drugs, there is a diminishing difference in the dose that provides the "rush" and a dose that can kill the user.
Physical Dependence
Physical dependence on opiate drugs evolves as the user's body adapts to the constant presence of the drug. Because tolerance induces changes in the body's cells, withdrawal of an opiate drug to which the body has become dependent causes an upset in cellular metabolic processes. The physical symptoms of opiate addiction become obvious with drug withdrawal and include yawning, excessive watering of the eyes and nose, anxiety, agitation, muscle and bone pain, insomnia, stomach upset and chills. The desire to avoid these unpleasant physical symptoms often causes users to resume opiate use despite the desire to quit, says the text "Essential Psychopharmacology."
References
- "Clinical Textbook of Addictive Disorders (Third Edition)"; Richard J. Francis et al.; 2005
- "Essential Psychopharmacology: Neuroscientific Basis and Practical Applications (2nd Edition)"; Stephen M. Stahl; 2002
- "Drug and Alcohol Abuse: A Clinical Guide to Diagnosis and Treatment (Sixth Edition)"; Marc A. Schuckit; 2006
