Drug and Alcohol Abuse – Important topic of Class 12 Biology Biology notes for Class 12 : Drug and Alcohol Abuse What is a Drug? In pharmacology (branch of medicine concerned with the uses, effects, and modes of action of drugs), a pharmaceutical drug, also called a medication or medicine, is a chemical substance used to treat, cure, prevent, or diagnose a disease or to promote well-being. In general, a drug is any substance (with the exception of food and water) which, when taken into the body, alters the body’s function either physically and/or psychologically. Drug abuse is an extreme desire to obtain, and use, increasing amounts of one or more substances. Drug abuse is a generic term for the abuse of any drug, including alcohol and cigarettes. Drug abuse is not the same thing as drug dependence or drug addiction. Drug dependence or addiction indicates a psychological or physical dependence on the drug for the body function. Drug dependence shows the symptoms of withdrawal if the drug is discontinued, whereas drug abuse does not. Watch animated video of Class 12 Biology by clicking Biology Class 12 Drug or alcohol problems (sometimes also called substance abuse or misuse) are a pattern of harmful behavior involving the misuse or overuse of substances for mood-altering purposes. This means that the drug or alcohol changes how a persona person who abuses alcohol has a greater risk of using at least one other substance, such as marijuana,