Chloroquine and hydroxychloroquine have been touted as potential treatments for COVID-19 patients, however clinical data is still very limited and the beneficial effects of these medicines in COVID-19 have not been demonstrated.
Chloroquine and hydroxychloroquine are currently authorised to treat malaria and certain autoimmune diseases. However, they are known to potentially cause serious adverse reactions such as heart rhythm problems, kidney problems and hypoglycaemia.
A number of large, randomised clinical trials have commenced in Europe, although some are using higher doses than recommended for the current authorised indications. While serious side effects can occur with recommended doses, higher doses can increase the risk of these side effects, including abnormal electrical activity that affects the heart rhythm (QT-prolongation). Therefore, the European Medicines Agency (EMA) has warned that these medicines should only be used as part of clinical trials or in line with nationally agreed protocols, in the context of COVID-19. They must not be used without a prescription and without supervision by a doctor.
Along with clinical trials, the US Food and Drug Administration (FDA) recently issued an emergency use authorisation (EUA), allowing the drugs to be used to treat hospitalised COVID-19 patients who are unable to participate in clinical trials and if the health care provider feels the potential benefit to the patient outweighs the potential risk. Case reports in the FDA Adverse Event Reporting System (FAERS) database and published medical literature have described “QT interval prolongation, ventricular tachycardia and ventricular fibrillation, and in some cases death,” from both hospital and outpatient settings.
Several small American studies have found little benefit from the drugs and the National Institutes of Health (NIH) have said there is “insufficient clinical data to recommend either for or against using chloroquine or hydroxychloroquine for the treatment of COVID-19.”
As a result of the risks the FDA has advised caution, and says the drugs should only be used under the EUA or in clinical trials. Patients treated with the drugs should be closely monitored, including monitoring baseline ECG, electrolytes, and renal and hepatic function.
The World Health Organisation (WHO) is concerned by reports of self-medication with chloroquine, which may lead to serious harm. Patients and healthcare professionals are reminded to report any suspected side effects to their national regulatory authorities.