Chloroquine and its derivatives are commonly prescribed for the treatment of malaria. The President of the United States, Donald Trump, announced at a White House briefing that he has begun taking the antimalarial drug hydroxychloroquine for preventive purposes, despite the World Health Organization’s statements that there is no compelling evidence that this drug is effective in combating the coronavirus.
In addition, the U.S. Food and Drug Administration (FDA) issued an advisory in April stating that there is no evidence that hydroxychloroquine is safe and effective for coronavirus. Regarding prevention of Covid-19 with this drug, there is currently no compelling evidence that hydroxychloroquine or similar drugs can prevent coronavirus infection, although clinical trials are underway in several countries, including the United States, United Kingdom, Spain and China.
Hydroxychloroquine is a later and less toxic version of chloroquine and has more pronounced antiviral and anti-inflammatory effects. Chloroquine is commonly used to treat malaria, certain parasitic infections, rheumatoid arthritis, and lupus erythematosus. Both drugs are cardiotoxic and may cause arrhythmias and tachycardia, especially in patients with pre-existing cardiovascular disease, as previously warned by the FDA in connection with the use of these two drugs for the treatment of Covid-19 in outpatient settings or during clinical trials.
According to a clinical trial conducted in the US on 368 patients at a veterans’ hospital, the death rate among Covid-19 patients taking hydroxychloroquine was higher than among those receiving standard treatment. Professor Catherine Selhi-Radtke, Vice President of the International Society for Antiviral Research, also believes that chloroquine is receiving undue attention in the absence of evidence of its efficacy in Covid-19. “More importantly, it can have dangerous side effects and give people false hope,” the professor wrote on the website sciencealert.com.
According to Friday’s Washington Post, a study of 96,000 patients who took hydroxychloroquine showed that their risk of developing an irregular heartbeat was significantly increased. This is the most comprehensive review of the side effects of this drug to date. Because the strain of the coronavirus SARS-CoV-2 that causes Covid-19 is new and poorly understood, there are currently no approved drugs to help the patient’s body cope with the complications it causes. Therefore, doctors around the world in such situations may resort to the practice of using some available drugs off-label, that is, not for their direct purpose.
In the provisional recommendations of the Ministry of Health of the Russian Federation on the prevention, diagnosis and treatment of Covid-19, antimalarial drugs are indicated as promising. “Among the drugs that are considered promising for the treatment of COVID-19, it is worth mentioning the group of antimalarial drugs: chloroquine, hydroxychloroquine and mefloquine. These drugs are used to treat malaria and some other parasitic infections,” the recommendations state. It is also noted that the mechanism of action of antimalarial drugs in viral infections is not fully understood, but there is reason to believe that they may inhibit the virus from entering the cell and replicating.
“In small clinical trials, it has been shown that the combination of [antibiotic] azithromycin with hydroxychloroquine enhances the antiviral effect of the latter,” according to the Department of Health manual. At the same time, there is a warning that special attention should be paid to the patient’s ECG before starting antimalarial therapy, as chloroquine and its derivatives can cause QT prolongation (ventricular tachyarrhythmia).
In late April, Nikolay Plavunov, the head of the Moscow Ambulance Service who contracted Covid-19, confirmed in an interview with the BBC that he had been treated with hydroxychloroquine in combination with antibiotics. “I took azithromycin first, then pneumonia started, so I added levofloxacin. It was quite effective,” the doctor said in the interview. He also acknowledged that there is a prevention system among Russian doctors, and in response to the question “Even with hydroxychloroquine?” he replied: “Including yes. It is clear that the employees have already somehow realized this, there are no more refusals of prevention”.
The guidelines of the Ministry of Health also mention that under the conditions of the pandemic, drug prophylaxis with chloroquine, hydroxychloroquine and mefloquine is being implemented in a number of countries. As for Russia, such prophylaxis is only recommended for certain populations in two cases: for postcontact prophylaxis after a single contact with a confirmed case of COVID-19 and for prophylaxis in individuals living in an infection hotspot.
Several patients, including a doctor from one of the Moscow clinics, confirmed to BBC correspondents that after testing positive and going into home isolation, they were given drugs for treatment, including Imard and antibiotics. These drugs disappeared from Moscow pharmacies in the second half of March, although they have always been available only on prescription. For example, in the list of side effects in the Russian instructions for Emgard, there are more than 40 possible adverse effects, ranging from psychosis and corneal clouding to cardiomyopathy and alopecia.
In the US, the FDA approved the use of chloroquine and hydroxychloroquine for the treatment of Covid-19 in limited cases in the hospital setting as an emergency measure at the end of March. In France, doctors can also prescribe these drugs to patients with coronavirus. In India, the use of hydroxychloroquine is recommended for health care workers and those who come into contact with coronavirus-infected individuals who have received a prescription from their treating physician. In a number of Middle Eastern countries, such as Bahrain, Morocco, Algeria and Tunisia, the use of these drugs is permitted or clinical research is underway. At the same time, experts worldwide warn against self-administration and uncontrolled use of antimalarial drugs, stressing that they should only be used as experimental medicines and only in emergencies.