Thiopental: Route Of Administration And Contraindications

Thiopental is a drug used as an anesthetic. It belongs to the barbiturate family and is also known as sodium thiopentate.

Thiopental is a drug used as a general anesthetic. Specifically, this substance belongs to the group of barbiturates, used as sedatives and analgesics for its depressant action on the central nervous system. We can also find it under the name of sodium thiopentate since it is a drug derived from thiobarbituric acid.

Today it is little used since there are other drugs that produce fewer side effects at lower doses. Patients commented that upon waking from anesthesia they felt slow and slightly disoriented, in fact almost all said that it was similar to the state of hangover after drinking alcohol.

Either way, it is an ultrashort-acting drug that was experimented with to induce the patient into a state of hypnosis. In the end it was denied because it was scientifically proven that it was only an anesthetic that lasted a few minutes.

What is the mechanism of action of thiopental?

Thiopental, like all barbiturates, binds to GABA receptors. This mechanism of action is the same as other relaxants, such as benzodiazepines (although the receptor subtype is different).

When the substance binds to the receptor, they form a binding complex that modulates the transmission of information to the central nervous system.

As a final result of the interaction, the sedative and anesthetic effect is produced. If there are seizures, it will also block them by modulating the neurotransmitter GABA, which is why it is also used as an anticonvulsant.

By sedating the patient, the person enters a state of tranquility that reduces brain metabolism. As the nutrient requirements are very low, the blood supply also decreases. For this reason it serves to reduce blood flow and, therefore, intracranial pressure.

What is thiopental used for?

The main indication for the use of thiopental is endotracheal intubation. Its characteristics of being a drug with ultra-short anesthetic action make it the perfect candidate. What is most interesting in this regard is that with very low doses it allows the pharyngeal reflex to be abolished, thus facilitating intubation.

This is especially useful in emergency situations where the patient is not ventilating correctly and has suffered some type of trauma to the mouth so that there is blood, foreign bodies (objects, teeth, etc.) that make it difficult to visualize the route to intubate. In this case, inhalation anesthesia is usually chosen.

It can also be used as a general anesthetic in short procedures. Although, as we have mentioned previously, little by little it has become obsolete and the use of other types of drugs is usually preferred. Mainly because it is anesthetic and sedative, but not analgesic. That is, it does not reduce pain. It just relaxes the patient.

There are very specific situations in which it can be an option to consider. For example, refractory cranial hypertension in patients with head trauma can be used to prepare for neurosurgery.

For psychiatric patients who have seizures that do not respond to other treatment, it can also be used.

What are the contraindications of thiopental?

There are several contraindications of thiopental that can be summarized in the following points:

• Hypersensitivity to barbiturates: this means that with a small dose, the effect on the patient is very intense and long-lasting. Being anesthetics it can cause respiratory depression.

• Mix it with other central nervous system depressants: especially alcohol. Since they work in a very similar way and enhances the effect.
• Pregnancy and breast-feeding: thiopental passes to the fetus and, therefore, causes depression of the baby’s nervous system.
• Jobs that require handling dangerous substances or driving vehicles: Its sedative effect reduces the ability to concentrate.

What are the routes of administration of thiopental?

Thiopental is always used intravenously with the exception of inhalational anesthesia for intubation. There are varieties in the dosage, but the normal thing is to use injectables of 2-4 mg / kg, taking into account that this dose is variable and that each person has a different sensitivity, so you have to start with the lowest amount and go up little. to little.

The maximum effect is achieved one minute after administration and, as we have mentioned previously, lasts a few minutes if it is not stabilized with a maintenance dose.