n. any of a group of drugs, derived from barbituric acid, that depress activity of the central nervous system and were formerly widely used as sedatives and hypnotics. They are classified into three groups according to their duration of action – short, intermediate, and long. Because they produce *tolerance and psychological and physical *dependence, have serious toxic side-effects (see barbiturism), and can be fatal following large overdosage, barbiturates have been largely replaced in clinical use by safer drugs. The main exception is the very short-acting drug *thiopental, which is used to induce anaesthesia. See also amobarbital; butobarbital; phenobarbital.
A group of drugs which depress the CENTRAL NERVOUS SYSTEM by inhibiting the transmission of impulses between certain neurons. Thus they cause drowsiness or unconsciousness (depending on dose), reduce the cerebral metabolic rate for oxygen, and depress respiration. Their use as sedatives and hypnotics has largely been superseded by more modern drugs which are safer and more e?ective. Some members of this group of drugs – for instance, phenobarbitone – have selective anticonvulsant properties and are used in the treatment of GRAND MAL convulsions and status epilepticus (see EPILEPSY). The short-acting drugs thiopentone and methohexitone are widely used to induce general ANAESTHESIA. (See also DEPENDENCE.)... barbiturates
A group of sedative drugs that work by depressing activity within the brain. They include thiopental and phenobarbital. In the past, barbiturates were widely used as antianxiety drugs and sleeping drugs but have been largely replaced by benzodiazepine drugs and other nonbarbiturates. Barbiturates are now strictly controlled because they are habit-forming and widely abused. An overdose can be fatal, particularly in combination with alcohol, which dangerously increases the depressant effect on the brain (including suppression of the respiratory centre). However, phenobarbital is still commonly used as an anticonvulsant drug in the treatment of epilepsy. Thiopental is very short acting and is used to induce anaesthesia (see anaesthesia, general).... barbiturate drugs
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