Chloroquine and hydroxychloroquine are not licensed to treat COVID-19 related symptoms or prevent infection, the agency said in a statement.
'Clinical trials are ongoing to test chloroquine and hydroxychloroquine as an agent in the treatment of COVID-19 or to prevent COVID-19 infection,' read the statement. 'These clinical trials are still not completed, so no conclusions have been reached on the safety and effectiveness of this medicine to treat or prevent COVID-19.'
'Until we have clear, definitive evidence these treatments are safe and effective for the treatment of COVID-19, they should only be used for this purpose within a clinical trial.'
Attention has focused on chloroquine and hydroxychloroquine as possible treatments for COVID-19 after unpublished data were reported from an open-label, non-randomised controlled study of hydroxychloroquine in 36 patients in France, and from a subsequent uncontrolled study of the drug by the same investigators in 80 patients. However, other experts have criticised the group's conclusions and say their findings are in line with the natural course of the infection.
The French study followed investigations by Chinese researchers which suggested that hydroxychloroquine could stop SARS-CoV-2, the virus responsible for COVID-19, entering cells. But a subsequent clinical study in 30 patients in China, albeit small-scale, found that those who were treated with the drugs fought off coronavirus no more quickly than those who did not receive the drugs.
Both Italy and France have said doctors can now prescribe hydroxychloroquine to treat COVID-19, despite the lack of evidence that it is effective. In the US, the FDA has issued an emergency use authorisation for both hydroxychloroquine and chloroquine, allowing the drugs to be donated to the national stockpile 'to be distributed and prescribed by doctors to hospitalized teen and adult patients with COVID-19, as appropriate, when a clinical trial is not available or feasible.'
Concerns have arisen that unproven claims of efficacy against COVID-19 could lead to hydroxychloroquine and chloroquine supplies being diverted from where they are most needed.
The drugs are used to treat a variety of rheumatological conditions including lupus, for which hydroxychloroquine is the mainstay of treatment. The charity Lupus UK said last week that it is receiving increasing numbers of reports from people with lupus who have been unable to obtain their hydroxychloroquine prescription, with their pharmacist currently unable to order the medication from their suppliers.
Lupus UK said it has written, along with other members of the Rare Auto-Immune Rheumatic Disease Alliance, to the Secretary of State for Health and Social Care and the Chief Pharmaceutical Officer, asking them to ensure that the supply of hydroxychloroquine to patients remains secure.
Chloroquine and hydroxychloroquine were recently added to the list of drugs banned from being parallel-exported. India has also banned the drug's export.