Stimulant & Depressants
Stimulants: Any drug that excites any bodily function; usually one that stimulates the central nervous system, inducing alertness, elevated mood, wakefulness, increased speech and motor activity, and decreased appetite. Their mood-elevating effects make some stimulants (e.g., amphetamines, caffeine and its relatives, cocaine, nicotine) potent drugs of abuse Ritalin, prescribed for attention deficit disorder in children, is a mild stimulant.
Depressants: any one of various substances that diminish functional activity, usually by depressing the nervous system. Barbiturates, sedatives, alcohol, and meprobamate are all depressants. Depressants have various modes of action and effects. Some are primarily used medically to relieve emotion stress, anxiety, and tension; others induce sleep, and still others are used to relieve pain. Depressants also reduce the rate and force of contraction of the heart and are used in the treatment of some forms of heart disease. Many depressants can induce psychological dependence and addiction (sees drug addiction and drug abuse). Typically, over dosage results in confusion, coma, and convulsions. In many cases, the effects of one depressant are intensified if another depressant is taken at the same time, e.g., if barbiturates are taken with alcohol. Because of their potential for abuse, there are now strict regulations regarding the dispensing of many depressant drugs.