Experiments are currently being conducted in a number of countries with drugs derived from chloroquine and hydroxychloroquine, in addition to other molecules, to treat people with Covid-19 epidemic. What do we know about these two components, between tests, studies and uses?

What is "chloroquine"?

"Chloroquine" is a compound form of quinine extracted from eucalyptus, used for centuries to treat malaria.

Chloroquine is sold under several names, according to countries and laboratories, and is known as nivakin or risokin.

As for hydroxychloroquine, it is derived from chloroquine, but it is less toxic than it, known in France under the name Plaquenil, and it is used to treat rheumatoid arthritis and lupus.

Why is there hope?

Waiting for a vaccine that is not known when it will be reached, and will certainly not be ready a year ago, scientists are testing existing drugs and mixing them in an effort to find a cure as soon as the Covid-19 pandemic sweeps the world.

Chloroquine and hydroxychloroquine are distinguished from other molecules by the availability and known, and their price is low.

The two drugs were known before the spread of the Covid-19 epidemic, and their antiviral properties were the subject of many studies, whether in the laboratory or on different animals and viruses.

"It has been known for a long time that chloroquine and the derivative hydroxychloroene disrupted in vitro experiments the multiplication of some viruses," said researcher in microbiology, specializing in infectious diseases at the Pasteur Institute Mark Marcoy. And he added that recent experiments confirmed, "as was expected, that the two substances already have in the laboratory an anti-virus" on the emerging corona virus, but "this does not necessarily assume that these two drugs have antiviral action in the human body", citing in this regard "several experiments". Disappointing »on the dengue virus, where they had no effect, and on chikungunya, where these molecules actually“ helped ”the virus to grow.

Scientific controversy

Three studies, one Chinese and two French, reported positive results in patients with the emerging coronavirus.

Chinese experiments included 134 people in different hospitals, and concluded that chloroquine had a positive effect.

In France, Professor Didier Raoul is experimenting with hydroxychloroquine.

After a first study of 20 patients, a second study was published Friday evening, this time on 80 patients, all of whom received a treatment that included a mixture of hydroxychloroquine and azithromycin, a well-known antibiotic used to eliminate secondary bacterial infections.

"We confirm the efficacy of the use of hydroxychloroquine, in conjunction with azetromycin in the treatment of Covid-19," he wrote with his team from the university hospital institute "Directorate de Infinixion" in Marseille.

However, many scientists, joined by the World Health Organization, stressed the limits of these studies, as they were conducted without taking into account the usual scientific principles followed, such as choosing patients by lottery, and conducting experiments without the participants or doctors knowing who is actually receiving treatment.

In evidence of the complexity of the topic, another Chinese clinical study published its findings on March 6 did not conclude a special efficacy of the drug on 30 patients.

Many side effects

Some of the scientific community and health authorities warn against rushing into the approval of these properties. "One of the uncalculated consequences could be the loss of chloroquine in what people need to treat rheumatoid arthritis," said Peter Bates, a former official with the US Food and Drug Administration.

The side effects are many, from nausea and rashes, to eye diseases, and cardiac and neurological disorders.

"Chloroquine" and "Hydroxychloroquine" are known before the spread of the "Covid-19" epidemic.