The 4-aminoquinolines, chloroquine, and hydroxychloroquine have been used for over 70 years for malaria and rheumatological conditions, respectively. Their broad-spectrum antiviral activity, excellent safety profile, tolerability, low cost, and ready availability made them prime repurposing therapeutic candidates at the beginning of the COVID-19 pandemic.
We applied a set of in silico and in vitro assays, compliant with the CiPA (Comprehensive In Vitro Proarrhythmia Assay) paradigm, to assess the risk of chloroquine or hydroxychloroquine-mediated QT prolongation and Torsades de Pointes (TdP), alone and combined with erythromycin and azithromycin, drugs repurposed during the first wave of COVID-19. Each drug or drug combination was tested in patch clamp assays on 7 cardiac ion channels, in in silico models of human ventricular electrophysiology (Virtual Assay® ) using control (healthy) or high-risk cell populations, and in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes.
Substantial efforts have been recently committed to develop COVID-19 medications, and Hydroxychloroquine alone or in combination with Azithromycin has been promoted as a repurposed treatment. While these drugs may increase cardiac toxicity risk, cardiomyocyte mechanisms underlying this risk remain poorly understood in humans. Therefore, we evaluated the pro-arrhythmia risk and inotropic effects of these drugs in the cardiomyocyte contractility-based model of the human heart. We found Hydroxychloroquine to have a low pro-arrhythmia risk, while Chloroquine and Azithromycin were associated with high risk.
Hydroxychloroquine, used to treat malaria and some autoimmune disorders, potently inhibits viral infection of SARS coronavirus (SARS-CoV-1) and SARS-CoV-2 in cell-culture studies. However, human clinical trials of hydroxychloroquine failed to establish its usefulness as treatment for COVID-19. This compound is known to interfere with endosomal acidification necessary to the proteolytic activity of cathepsins. Following receptor binding and endocytosis, cathepsin L can cleave the SARS-CoV-1 and SARS-CoV-2 spike (S) proteins, thereby activating membrane fusion for cell entry.
Clinical trials of hydroxychloroquine (HCQ) for the treatment of coronavirus infection 2019 (COVID-19) are moving forward on the heels of conflicting, and sometimes controversial, observational studies out of China and France from the first months of the pandemic [1–3].
COVID-19 has been a threat throughout the world since December 2019. In attempts to discover an urgent treatment regime for COVID-19, hydroxychloroquine (HCQ) and chloroquine (CQ) have been on solidarity clinical trial. However, many countries have pulled HCQ and CQ from their COVID-19 treatment regimens recently, some countries still continue using them for patients who have previously started HCQ and CQ and they may complete their course under the supervision of a doctor. HCQ and CQ are 4-aminoquinoline drugs and it is safe to use them for autoimmune diseases, rheumatoid arthritis, systemic lupus erythematosus and malaria as well.
In clinical practice chloroquine and hydroxychloroquine are often co-administered with other drugs in the treatment of malaria, chronic inflammatory diseases, and COVID-19. Therefore, their metabolic properties and the effects on activity of cytochrome P450 (P450, CYP) enzymes and drug transporters should be considered into when developing the most efficient treatments for patients.
In the absence of a vaccine the medical and scientific community is looking intensely at utilizing a pre or post exposure drug that could decrease viremia. The search for a medication that could reduce risk of serious disease, and ideally of any manifestation of disease from SARS-CoV2, and of asymptomatic shedding of SARS-CoV2 is of urgent interest. Repurposing existing pharmaceuticals is among the approaches to achieve these ends.
The claim that anti-malaria drugs, chloroquine and hydroxychloroquine, can cure COVID-19 became a focus of fierce political battles that pitted promoters of these pharmaceuticals, Presidents Bolsonaro and Trump among them, against "medical elites." At the center of these battles are different meanings of effectiveness in medicine, the complex role of randomized clinical trials (RCTs) in proving such effectiveness, the task of medical experts and the state in regulating pharmaceuticals, patients' activism, and the collective production of medical knowledge.
Chloroquine (CQ) and hydroxychloroquine (HCQ) are on the World Health Organization's List of Essential Medications for treating non-resistant malaria, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In addition, both drugs are currently used off-label in hospitals worldwide and in numerous clinical trials for the treatment of SARS-CoV-2 infection.