Recently, President Trump has noted the use of hydroxychloroquine and chloroquine as treatment options for patients with Covid-19 and subsequently ordered the FDA to grant approval on the grounds of compassionate use. This term is used to enable access to certain medications that would otherwise require a lengthy approval procedure, essentially allowing physicians to use an investigational drug under a protocol that undergoes review with an opportunity to collect additional data.
Hydroxychloroquine, which is sold by Concordia Pharmaceuticals under the brand name Plaquenil, and chloroquine are oral prescription drugs that have been used for many years to prevent and treat malaria and certain inflammatory conditions. Although these agents are well-established, they possess the potential to cause numerous side effects and should be used with caution in those who are diabetic, those with neurological disorders, and those with vision disorders. Recent data highlights how hydroxychloroquine retinopathy is more common than previously reported. Other side effects include cardiomyopathy and bone marrow suppression, but these are not commonly reported. Initial in vitro studies with hydroxychloroquine have demonstrated antiviral activity using severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected Vero cells. Additionally, in an article published in The Lancet on 19 March, the efficacy and safety of hydroxychloroquine were investigated for the treatment of pneumonia caused by the coronavirus in a pilot study of 30 patients. The initial outcome was deemed positive; however, the results showed that it had a comparable assessment of conventional treatment alone. The study prospectively observed a population of 30 patients with mild Covid-19, where hydroxychloroquine was administered at a dose of 400mg per day for five days (HCQ) and randomised against a control group. While 13 patients (86.7%) in the HCQ group cleared the virus on Day 7, 14 patients (93.3%) in the control group managed the same with conventional treatment alone. Furthermore, the median duration of hospitalisation to virus nucleic acid negative conversion was similar in both groups.
Other studies have suggested that a combination of hydroxychloroquine with azithromycin may beneficial to prevent severe respiratory tract disease in those diagnosed with Covid-19. However, further data are required, as these studies were small and there is not enough evidence to convincingly implement guidance on this. Furthermore, azithromycin is associated with prolonged cardiac repolarisation and QT interval, imparting a risk of developing cardiac arrhythmias. Therefore, extra caution is required when considering this combination.
Currently, there are not enough data to support hydroxychloroquine use for Covid-19 treatment at the level of expectations set by President Trump. As such, larger and more robust randomised clinical trials are needed to inform clinical guidance on the use, dosing, or duration of hydroxychloroquine for prophylaxis or the treatment of SARS-CoV-2 infection.
