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Anaesthesia => Barbiturates


Barbiturate, any of a group of drugs that depress brain function. Barbiturates are derived from barbituric acid (C4H4N2O3), a combination of urea and malonic acid.
Depending on the dosage or formulation, barbiturates have a sedative (tranquillizing), hypnotic (sleep-inducing), anticonvulsant, or anaesthetic effect. Very short-acting barbiturates are injected intravenously to induce rapid anaesthesia before surgery. Phenobarbitone, a long-acting barbiturate, is prescribed with other medicines to prevent epileptic seizures. Other barbituric-acid derivatives were used as anti-anxiety medications until the development of the tranquillizer; they are only used for short-term treatment of severe insomnia, as they have a high risk of toxic effects, tolerance leading to addiction, and adverse effects on the liver. Tranquillizers and new preparations are more suitable sleep inducers. However, none of these sleep-inducing drugs are for long-term use.
Barbiturates are common drugs of abuse. Taken orally or intravenously, they produce symptoms similar to drunkenness: loss of inhibition, boisterous or violent behaviour, muscle incoordination, depression, and sedation. Because they are physically addictive, and can cause drug dependence, symptoms from their withdrawal can be severe; overdoses can cause profound shock, coma, or death.