A barbiturate is a drug that acts as a central nervous system depressant. Barbiturates are effective as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as well as overdose potential among other possible adverse effects. They have largely been replaced by benzodiazepines and nonbenzodiazepines ("Z-drugs") in routine medical practice, particularly in the treatment of anxiety and insomnia, because of the significantly lower risk of addiction and overdose and the lack of an antidote for barbiturate overdose. Despite this, barbiturates are still in use for various purposes: in general anesthesia, epilepsy, treatment of acute migraines or cluster headaches, acute tension headaches, euthanasia, capital punishment, and assisted suicide.The name barbiturate originates from the fact that they are all chemical derivatives of barbituric acid. Uses
Medicine
Barbiturates, such as phenobarbital, were long used as anxiolytics and hypnotics. Intermediate-acting barbiturates reduce time to fall asleep, increase total sleep time, and reduce REM sleep time. Today they have been largely replaced by benzodiazepines for these purposes because the latter are less toxic in drug overdose. However, barbiturates are still used as anticonvulsants (e.g., phenobarbital and primidone) and general anesthetics (e.g., sodium thiopental). Barbiturates in high doses are used for medical aid in dying, and in combination with a muscle relaxant for euthanasia and for capital punishment by lethal injection. Barbiturates are frequently employed as euthanizing agents in small-animal veterinary medicine. Interrogation
Sodium thiopental is an ultra-short-acting barbiturate that is marketed under the name Sodium Pentothal.
Overdose
Some symptoms of an overdose typically include sluggishness, incoordination, difficulty in thinking, slowness of speech, faulty judgement, drowsiness, shallow breathing, staggering, and, in severe cases, coma or death. The lethal dosage of barbiturates varies greatly with tolerance and from one individual to another. The lethal dose is highly variable among different members of the class, with superpotent barbiturates such as pentobarbital being potentially fatal in considerably lower doses than the low-potency barbiturates such as butalbital. Even in inpatient settings, the development of tolerance is still a problem, as dangerous and unpleasant withdrawal symptoms can result when the drug is stopped after dependence has developed. Tolerance to the anxiolytic and sedative effects of barbiturates tends to develop faster than tolerance to their effects on smooth muscle, respiration, and heart rate, making them generally unsuitable for a long time psychiatric use. Tolerance to the anticonvulsant effects tends to correlate more with tolerance to physiological effects, however, meaning that they are still a viable option for long-term epilepsy treatment. Barbiturates in overdose with other CNS (central nervous system) depressants (e.g. alcohol, opiates, benzodiazepines) are even more dangerous owing to additive CNS and respiratory depressant effects. In the case of benzodiazepines, not only do they have additive effects, barbiturates also increase the binding affinity of the benzodiazepine binding site, leading to exaggerated benzodiazepine effects. (ex.