WASHINGTON, June 15 (Xinhua) -- The U.S. Food and Drug Administration (FDA) on Monday revoked the emergency use authorization (EUA) that allowed for chloroquine phosphate and hydroxychloroquine used to treat certain hospitalized patients with COVID-19, according a release of the agency.

Based on its ongoing analysis of the EUA and emerging scientific data, the FDA determined that chloroquine and hydroxychloroquine are unlikely to be effective in treating COVID-19 for the authorized uses in the EUA.

Additionally, in light of ongoing serious cardiac adverse events and other potential serious side effects, the known and potential benefits of chloroquine and hydroxychloroquine no longer outweigh the known and potential risks for the authorized use, said the release.

The FDA issued an EUA on March 28 to allow hydroxychloroquine and medical-grade chloroquine to be distributed from the Strategic National Stockpile and prescribed by doctors, to hospitalized adolescents and adults with COVID-19, when a clinical trial is not available or feasible.

"We've made clear throughout the public health emergency that our actions will be guided by science and that our decisions may evolve as we learn more about the SARS-CoV-2 virus, review the latest data, and consider the balance of risks versus benefits of treatments for COVID-19," said FDA Deputy Commissioner for Medical and Scientific Affairs Anand Shah.

A clinical trial to evaluate whether hydroxychloroquine, given together with antibiotic azithromycin, can prevent COVID-19 hospitalization and death, started in mid-May. The trial enrolls approximately 2,000 adults across the United States, who are infected with SARS-CoV-2, the novel coronavirus that causes COVID-19, and exhibiting symptoms of fever, cough or shortness of breath, according to the U.S. National Institutes of Health.

Recent results from the large randomized clinical trial in hospitalized patients, a population similar to the population for which chloroquine and hydroxychloroquine were authorized for emergency use, demonstrated that hydroxychloroquine showed no benefit on mortality or in speeding recovery, said the FDA

This outcome was consistent with other new data, including data showing that the suggested dosing regimens for chloroquine and hydroxychloroquine are unlikely to kill or inhibit the virus that causes COVID-19, according to the FDA.

"While additional clinical trials continue to evaluate the potential benefit of these drugs in treating or preventing COVID-19, we determined the emergency use authorization was no longer appropriate. This action was taken following a rigorous assessment by scientists in our Center for Drug Evaluation and Research," said Patrizia Cavazzoni, acting director of the FDA's Center for Drug Evaluation.

Chloroquine and hydroxychloroquine are approved by the FDA to treat or prevent malaria.