Originally, curares are known as a poison used by warriors of the Amazonian forests. This is where the name comes from, the meaning of which remains deadly: “the one who kills quietly”.

The curare is a natural product, resulting from the climbing lianas which one finds in the heart of the forests of Amazonia, and more particularly the species ” Chondrodendron tomentosum “. Warriors used it to design poison arrows, capable of paralyze enemies hit. Death is even possible, if the breathing muscles are affected, causing a asphyxia.

Nowadays, Amerindian warriors are no longer the only ones to use curares: they are found in our hospitals. Indeed, where a high dose can lead to death, used wisely curares can save lives. The poison was popularized by the doctor Claude Bernard (1813-1878), who discovered its action on the nervous system.

We use them in intravenous injection during’anesthésies or resuscitation, most often in order to relax the muscles of the body.

Curares have an effect of muscle relaxation. More specifically, they are able to relax the skeletal muscles, those whose contraction we can voluntarily control (for example those of the face or the respiratory action). By inserting themselves into the very heart of neural information, curares can prevent it from spreading. On the other hand, they do not affect the other muscles, nor the patient’s capacity to be conscious: one does not fall asleep with a curare, on the other hand one can paralyze.

Curares can be used in several settings:

To facilitate insertion

If it is absolutely necessary to introduce an artificial respiration system to a patient, and therefore to insert a tube at the back of his throat, curares make it possible to relax and relax the muscles of the jaw and therefore facilitate theintubation. This is very useful for inserting a tube, or during laparoscopy, when inserting a camera in surgery to directly observe the inside of the throat.

In order to set up artificial respiration

Likewise, the patient’s muscle movements can complicate the task of a life support ventilator. In order to optimize the latter, we can provide curare to the patient in order to relax his lung muscles. This use experienced strong demand during the Covid-19 epidemic, where many patients had to be urgently placed in intensive care. Until triggering shortages of curares.

In anesthesia, curare is often used after a hypnotic, an injection causing unconsciousness. Note that curares can be used in both adults and children, by adjusting the doses accordingly.

There are different types of curares, each with different doses:

• Suxamethonium (lasting 5-10 minutes);
• Rocuronium (lasting 40 to 60 minutes);
• Atracurium (lasting 30 to 40 minutes);
• Cisatracurium (lasting 45 to 90 minutes);
• Mivacurium (lasting 12-18 minutes);
• Vecuronium (lasting 30 to 40 minutes).

Suxamethonium belongs to the category of curares depolarizing. While the other five on the list are said ” non-depolarizing “. The difference lies in the mechanism of action of curare, the way in which they will block nerve information between muscle receptors. Concretely, the depolarizers will allow an action quick and short, while the “non-depolarizing” will be more slow but long.

Before the intervention

Curare is not recommended for patients with allergies or sensitivities, in order to avoid any side effects during medical intervention, and especially the anaphylactic shock. It is therefore better to ensure as a priority that the patient has no allergy to any of the components.

Curares are stored at low temperatures, between 0 and 10 ° C.

After curarization

Curare was not used as a poison for nothing: even after its paralyzing action, it can remain in the blood. It is therefore necessary to take a antidote after the medical operation, in order to eliminate all traces. Otherwise, some patients have breathing difficulties. Some of the most commonly used antidotes are neostigmine and sugammadex.

The use of curares is not without risk, and there are several undesirable side effects:

• Allergic and anaphylactic shock risk;
• Myalgia (muscle pain);
• Hyperkalaemia (increased level of potassium in the blood).