Abstract
Drug abuse can be defined as an inappropriate use of a drug for a nonmedical purpose. On the basis of common pharmacologic actions and cross-tolerance and cross-dependence, the major drugs of abuse can be divided into distinct categories: opioid analgesics; general depressants of the CNS, including sedative-hypnotics, antianxiety drugs, and alcohol; cocaine, amphetamines, and related psychomotor stimulants; hallucinogens; marijuana; and inhalants. In the following discussion, each drug group is described in terms of three major factors: (1) the pharmacologic effects produced by the drug group; (2) the abuse characteristics of the drug group, including addiction, tolerance, dependence, withdrawal, and other characteristics; and (3) the toxicity caused by the drug group and how it is treated.