Kremlin critic: was Navalny poisoned with Novichok?

Icon: enlarge

Alexej Navalny at a rally for the politician Boris Nemtsov, who was murdered in 2015

The doctors at the Berlin Charite have found evidence of poisoning in the case of the Russian opposition politician Alexej Navalny. The clinical findings would point to a substance from "the active ingredient group of cholinesterase inhibitors," said the Charite. The exact substance is not yet known.

What do you know about the active ingredient?

Some drugs and insecticides, but also nerve toxins such as Novichok, which was developed in the former Soviet Union, are based on the active ingredients from this group. These substances inhibit the enzyme "acetylcholinesterase", which is important for the normal functioning of the nervous system in humans, vertebrates and insects.

In the human body, the enzyme is responsible for breaking down messenger substances; it conducts stimuli from nerve cell to nerve cell. In the case of serious illnesses such as Alzheimer's, it makes sense to hinder this function, for example if there is a lack of messenger substances. Here, cholinesterase inhibitors in the form of drugs help to increase the "signal strength" of thinking.

When does the drug become poison?

Cholinesterase inhibitors can cause overactivity in a number of body functions, the acute consequences of which can be fatal. They can cause muscle cramps and then lead to cardiac and respiratory paralysis. Atropine, for example, is used as an antidote, which, among other things, interrupts the transmission of signals in the nerve conduction and weakens the effect of the poison. According to the Charité, Navalny is currently also being treated with it.

On the basis of a cholinesterase inhibitor, among other things, the now banned insecticide E 605 was produced, which was also used in homicides because of its deadly effect.

What does the active ingredient have to do with Novichok?

Neurotoxins such as sarin and novichok are based on the action of cholinesterase inhibitors. The Novichok poisons were developed in the Soviet Union in the 1970s and 1980s and have become notorious in recent years due to several sensational attacks. In 2018, Novichok was used in England in the assassination attempt on the Russian double agent Sergei Skripal. A few months later, a British couple came into contact with the substance and the woman died as a result.

The poison group consists of around a hundred different types of substance. Some of them are said to be five to eight times more deadly than the neurotoxin VX, which is said to have been used to murder the half-brother of North Korean leader Kim Jong Un. Compared to VX and Sarin, the Novitschok substances are more difficult to detect, but they can now still be detected.

The poisons are made from two non-toxic raw materials. The ingredients are quite easy to come by, explains Gary Stephens, a pharmacologist at the University of Reading. "The chemicals are not subject to strict regulations." They could be easily delivered because there is no risk to the health of the suppliers. The substances only develop their poisonous effect in combination.

The body absorbs the neurotoxin, like other substances from the active ingredient group, primarily through the respiratory tract, sometimes through the skin or mucous membranes. So far there is no evidence that Alexei Navalny was actually poisoned with Novichok.