When it comes to serum from the truththoughts might turn to the potion Veritaserum of Harry Potter, but from Diabolik to 007 there are countless pop culture characters who have used it in their adventures, not to mention the novel Kallocaine by Karin Boye. But does it really exist? We say yes, even if it is not entirely “truthful”. Technically, “truth serums” are psychoactive substances that allow information to be obtained without resistance from those who take them. The sodium thiopental it is the most famous molecule used as truth serum, also known by its commercial name Pentothal: reduces the ability to concentrate and, like alcohol, makes the subject vulnerable and compliant. Precisely for this reason, the so-called “confessions” obtained with Pentothal cannot be considered reliable and its use for this purpose is considered a method of torture.
What is truth serum and what is it for?
With the name “truth serum” have been called different cocktails of drugs and substances with the ability to reduce or slow down cognitive abilities and make the subject lose inhibitions so that he could not lie. Therefore, we could also consider substances such as wine and the alcohol of truth serums: after all, as the Romans said “in vino veritas”.
The substance best known as a component of truth serum is sodium thiopentalor sodium thiopental (often combined with other drugs or replaced by sodium amytal). Also known by the trade name of Penthotalthis molecule belongs to the class of barbiturates, sedative hypnotic drugs used since the early twentieth century treatment of anxiety and insomnia.
Highly addictive, they are responsible for multiple lethal overdoses of famous people, for example that of Marilyn Monroe and Elvis Presley. Precisely because of this danger, they are no longer used as sedative drugsnow supplanted by benzodiazepines, but are still used in some forms of narcotherapy, migraines and epilepsy.
How does it work on a biochemical level?
Like all barbiturates, Pentothal is a molecule lipophilic which easily crosses the barrier hematoencephalic (the barrier that protects the brain) and reaches the Central Nervous System (CNS) very quickly, where it binds to specific gamma-aminobutyric acid (GABA) receptors.
GABA is the inhibitory neurotransmitter par excellence: when Pentothal binds to its receptors, it keeps them active (or rather open, because these receptors are channels that let the chlorine ion pass) for longer. By doing so, it increases the inhibitory activity of GABA and consequently decreases neuronal activity. Sometimes, at high doses, it can even take the place of GABA.
To make a long story short, reduces the ability of neurons to communicate with each other. Furthermore, it also acts on receptors of other systems, for example by inhibiting excitatory glutamate receptors. So increases inhibitory stimuli and blocks excitatory ones: a perfect strategy to induce a state of sedation and semi-consciousness.
Truth serum is not reliable
So is it true that if we take this substance we always tell the truth? It’s not said. The concept behind the use of truth serum is that by slowing down neuronal activity, it is more difficult to carry out difficult tasks, concentrate And create complex thoughts, which is necessary if we intend to lie or hide something. So far, it would also make sense, the problem is that what we say in an altered mental state is not necessarily the truth.
Let’s take the example of alcohol again: when we are under the effects of alcohol, we all tend to become more talkative and lose our inhibitions, but also to be more compliant, sometimes for example we repeat or confirm what we are told by others people.
Here, barbiturates such as sodium thiopental work in a similar way: under their influence It’s harder to lie, but not impossible and furthermore, the person being questioned could “parrot” what he is told. For this reason the use of sodium thiopental and any substance used as truth serum in interrogations is considered unreliable and above all a form of torture.
The other uses of Pentothal
Pentothal was one of the drugs present in the cocktail of lethal injections in America, but it has been replaced and in Europe it has been export banned since 2011, as well as any other substance that can be used in capital punishment and torture.
To this day, it is still sometimes used in anaesthesia as second choice after Propofol, as indicated by the WHO List of Essential Medicines. However, compared to Propofol, the duration of anesthesia induced by sodium thiopental is shorter, because it is quickly redistributed from the brain to the other organs.
Sources
Katzung, General and Clinical Pharmacology, ed Piccin ISBN 978-88-299-1967-3
EU Commission – Commission extends control over goods which could be used for capital punishment or torture