Barbiturates, types and side effects

David Holt
Barbiturates, types and side effects

Barbiturates are a class of psychoactive substances derived from barbituric acid that act as central nervous system (CNS) depressants. They produce sedative effects and are effective as anxiolytics, hypnotics and anticonvulsants (to treat epilepsy).

They are very dangerous since there is no effective treatment to reverse a barbiturate overdose, it is for this reason that they were used for a long time as anxiolytics and hypnotics between the 60s and 70s, but today they have been replaced by benzodiazepines, which they are less toxic in case of overdose. However, barbiturates are still used as anticonvulsants (eg, phenobarbital and primidone) and general anesthesia.

Other uses of barbiturates in the 21st century are physician-assisted suicide (in countries and states where this procedure is legal), and as a lethal injection in convicted persons in the United States. They are also frequently used as euthanasia agents in veterinary medicine..


  • How barbiturates work
    • The truth serum
  • Side effects
    • Barbiturate overdose
  • Types of barbiturates
    • Amobarbital
    • Butalbital
    • Phenobarbital
    • Secobarbital
    • Pentobarbital
    • References

How barbiturates work

Barbiturates, as we have said, are central nervous system depressants. They work by enhancing the action of GABA, a neurotransmitter that inhibits the activity of nerve cells in the brain.

Thiopental or Sodium Thiopentate is an ultra-short-acting barbiturate that is marketed under the name of sodium pentothal, sodium amytal or trapanal. It is classified as an ultrashort-acting barbiturate because the hypnotic effect in small doses of the drug wears off within a few minutes. Currently it is little used due to the slow and heavy recovery of the patient. It was the first barbiturate introduced as an inducing agent in surgery in 1934 given its rapid effect as an inducer of anesthesia. Also, it has been used to induce medical coma states, to decrease brain metabolic requirements. Together with methohexital, it is the most widely used barbiturate in clinical anesthesia.

The truth serum

As a curiosity, pentothal has been used historically in psychiatry since it seemed to improve the fluidity of the patient's response. This is the use that has made this drug famous, and for what it is known as a truth serum. In controlled doses, its hypnotic action in the human brain produces depression of the higher cortical functions, which suggested that it could be useful in interrogations. The lie is considered to be a complex, conscious elaboration, much more complicated than the truth, so if the higher cortical activity deteriorates, the subject may find it much more difficult to maintain his will and presumably he will tend to tell the "truth" . That is, at least, the theory, and that is why it has been put into practice for decades by the espionage services of many countries. Up to a point, the idea is correct, but it does not guarantee, far from it, that the subject will tell what is expected, since there are many factors that can modify the results, from special training to environmental conditions or, simply, an assumption of the lie as truth.

On the other hand, Thiopental-induced memory and cognitive impairment is also believed to reduce a subject's ability to invent and remember lies. This practice is no longer considered legally admissible due to findings that subjects subjected to such interrogations can form false memories, calling into question the reliability of all information obtained through such methods. However, it is still used in certain circumstances by law enforcement and defense agencies as a "humane" alternative to torture interrogation when the subject is believed to possess information critical to the security of the state or agency employing the tactic..

Side effects

The pharmacological actions of barbiturates include depression of nerve activity in cardiac, smooth, and skeletal muscles. Barbiturates also affect the central nervous system in different ways and can produce effects ranging from mild sedation to coma, depending on the dose..

Low doses of barbiturates can lower anxiety levels and relieve tension, while higher doses can lower heart rate and blood pressure.

Barbiturates can be considered extremely addictive from a physical and psychological point of view. Shorter-acting barbiturates are significantly more addictive than longer-acting barbiturates.

Barbiturate overdose

Symptoms of a barbiturate overdose include severe mental slowdown, slurred speech, confusion, delusions, respiratory depression, coma, and death..

It is worth noting that the sudden discontinuation of barbiturates can be very dangerous and life-threatening for people who consume regularly for long periods of time, sometimes leading to seizures or even death, which is why it should be done in centers. sufficiently prepared clinicians.

Types of barbiturates


Commonly known as "sodium amytal" or "sodium pentothal," this barbiturate is the one that earned the reputation of being the real serum. While it doesn't really force people to tell the truth, amobarbital can slow down the central nervous system so that concentration becomes more difficult. The theory was that someone would ask a question while, under the influence of amobarbital, they would be less likely to think of a false answer, which requires more attention than simply telling the truth..


This short-acting barbiturate is frequently used to treat migraine headaches, often in combination with acetaminophen, aspirin, and caffeine. It has also been used as a sedative and anesthetic.


This barbiturate was used to treat seizures in children, due to its anticonvulsant function. It has also been used to treat anxiety, drug withdrawal (particularly from other barbiturates), and as a sleep aid..


Marketed in the US as Seconal beginning in 1934, this drug was prescribed for many years to combat insomnia. It is the drug most used in physician-assisted suicides in that country..


Used as an anesthetic in animals, this drug was used in the past to treat fits and seizures. It also has the dubious distinction of being one of the drugs of choice for the executions of prisoners in the United States..


Sota Omoigui's Anesthesia Drugs Handbook. Sota Omoigui. Editorial State-Of-The-Art Technologies Inc, Third Edition

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