Washington, April 24 : At a time when hydroxychloroquine (HCQ) is being touted as a 'wonder drug' to treat critical Covid-19 patients, the US Food and Drug Administration (FDA) on Friday issued fresh guidelines, cautioning people against over-the-counter use of hydroxychloroquine or chloroquine for Covid-19 outside of the hospital setting or a clinical trial due to the risk of heart rhythm problems.
The FDA said it is aware of reports of serious heart rhythm problems in patients with Covid-19 treated with hydroxychloroquine or chloroquine, often in combination with azithromycin and other QT prolonging medicines.
"We are also aware of increased use of these medicines through outpatient prescriptions.
Therefore, we would like to remind healthcare professionals and patients of the known risks associated with both hydroxychloroquine and chloroquine," the agency said in a statement.
Hydroxychloroquine, an anti-malarial drug termed potential "game changer" for Covid-19 by US President Donald Trump, has disappeared from medical stores globally, including in India, putting millions at risk of self-medicating themselves with the drug.
The FDA said that it will continue to investigate the risks associated with the use of hydroxychloroquine and chloroquine for Covid-19.
"Hydroxychloroquine and chloroquine have not been shown to be safe and effective for treating or preventing Covid-19.
They are being studied in clinical trials for Covid-19, and we authorised their temporary use during the Covid-19 pandemic for treatment of the virus in hospitalised patients when clinical trials are not available, or participation is not feasible, through an Emergency Use Authorisation (EUA)," elaborated the FDA.
Hydroxychloroquine and chloroquine can cause abnormal heart rhythms such as QT interval prolongation and a dangerously rapid heart rate called ventricular tachycardia.
Hydroxychloroquine, alone or in combination with azithromycin, is being used in Covid-19 therapy based on anecdotal and limited observational evidence in several countries.
Despite limited and conflicting data on the use of hydroxychloroquine in patients with Covid-19, the US FDA has authorised the emergency use of this drug when clinical trials are unavailable or infeasible.
"The risks may increase when these medicines are combined with other medicines known to prolong the QT interval, including the antibiotic azithromycin, which is also being used in some Covid-19 patients without FDA approval for this condition," cautioned the agency.
"Patients who also have other health issues such as heart and kidney disease are likely to be at increased risk of these heart problems when receiving these medicines," it added.
Patients taking hydroxychloroquine or chloroquine for FDA-approved indications to treat malaria or autoimmune conditions should continue taking their medicine as prescribed.
"The benefits of these medicines outweigh the risks at the recommended doses for these conditions.
Do not stop taking your medicine without first talking to your healthcare professional," warned the FDA statement.
Be aware that there are no proven treatments for Covid-19 and no vaccine, it said.
"Do not buy these medicines from online pharmacies without a prescription from your healthcare professional.
Consumers should not take any form of chloroquine that has not been prescribed for them by a healthcare professional," the FDA noted.
Serious poisoning and death have been reported after mistaken use of a chloroquine product not intended to be taken by humans.