US, WASHINGTON (ORDO NEWS) — Brazilian scientists have stopped taking high doses of chloroquine, a relatively inexpensive drug commonly used to treat and prevent malaria, as part of its clinical trials against coronavirus disease.
According to the researchers report published on the preprint portal medRxiv.org (work has not yet been reviewed), 81 patients were hospitalized with ARVI in the city of Manaus (Brazilian state of Amazonas). Subsequently, in almost half of them (49.4%), Covid-19 was detected by reverse transcription by polymerase chain reaction.
The study participants were divided into two groups: the first (41 people) was supposed to receive a dose of 600 milligrams of chloroquine twice a day for 10 days, the second (40 people) – 450 mg two times on the first day, and then once every five days.
Patients older than 75 years old were included in the high-dosage group, and the study itself was carried out by a double-blind method – neither the patients nor their doctors knew what dose they were receiving. In parallel, all subjects took ceftriaxone (a broad-spectrum antibiotic of the cephalosporin series) and azithromycin (a macrolide antibiotic prescribed for the treatment of bacterial infections).
However, on the sixth day, the study had to adjust and suspend the recruitment of patients in the first group. As the scientists explained, preliminary results showed that taking high doses of chloroquine for 10 days cannot be recommended in the treatment of Covid-19 because of the risk of disturbances in the normal (sinus) rhythm of the heart, characterized by rapid contraction of the ventricles.
“Taking large doses of chloroquine <…> tended to increase mortality (17%) than the lower dosage. <…> On the fourth day, airway secretion was negative in only one patient. <…> Mortality was 13.5%. Only two out of 11 deaths occurred among patients over 75 years of age. Eight of the 11 deaths had confirmed Covid-19 to death. Based on the data received, the Data Verification and Safety Commission recommended that the high dose be stopped immediately. All patients from this group are obliged to return to taking a low dose of chloroquine, ”the authors report.
The results of this study should be the “red flag” for scientific groups around the world to “avoid even more unnecessary deaths,” the scientists concluded.
Last month, U.S. President Donald Trump said the Food and Drug Administration (FDA) approved the use of hydroxychloroquine (developed on the basis of the synthetic analogue of quinine (chloroquine)) and chloroquine for the treatment of patients with new types of coronavirus.
Pres. Trump touts chloroquine, an old malaria drug, that doctors say may help treat novel coronavirus, claims it will be available "almost immediately."
— ABC News (@ABC) March 19, 2020
According to the Centers for Disease Control and Prevention (CDC), both drugs are generally well tolerated at the doses prescribed by doctors, but can cause abdominal pain, nausea, vomiting, headache and sometimes itching, and with long-term use at high doses, they can lead to the development of retinopathy (damage to the retina of the eyeball).
Patients suffering from psoriasis should not be prescribed hydroxychloroquine and chloroquine. In addition, as noted in the CDC, in their current form, drugs may not be safe for people with cardiac arrhythmias and kidney or liver problems.
The FDA, in turn, clarified that it was solely that “doctors could prescribe these drugs to adolescents and adults hospitalized in connection with Covid-19, depending on the circumstances when a clinical trial is not available or inappropriate.”
At the same time, health workers and patients themselves should be aware of the “known risks”, since doctors have previously stated that chloroquine can sometimes cause life-threatening heart rhythm disturbances. Both drugs have yet to be evaluated in clinical trials before they are declared safe and effective for the treatment of Covid-19, agency officials said.
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