barbiturate
n. any of a family of drugs derived from barbituric acid that depress activity of the central nervous system (see CNS depressant) and were previously widely used as anxiolytics, sedatives, hypnotics, and general anesthetics. They typically induce profound tolerance and withdrawal symptoms and depress respiration. Moreover, they can depress breathing completely—hence their use by individuals wishing to commit suicide. Barbiturates are commonly categorized according to their rates of action (including onset of effect, absorption, and excretion) as long acting, intermediate acting, short acting, or ultrashort acting. Their use became common in the 1930s, but they were rapidly supplanted in the 1970s by the benzodiazepines, which lack the lethality associated with overdose of the barbiturates. The group includes amobarbital, butabarbital, pentobarbital, phenobarbital, primidone, and
thiopental, among others. See sedative, hypnotic, and anxiolytic drug. The prototype of the group, barbital, was introduced into medical practice in 1903.