Risk of drug-induced Long QT Syndrome associated with the use of repurposed COVID-19 drugs: a systematic review

Background: The World Health Organization first declared SARS-CoV-2 (COVID-19) a pandemic on March 11, 2020. There are currently no vaccines or therapeutic agents proven efficacious to treat COVID-19. So, whether existing approved drugs could be repurposed and used off-label for the treatment of novel COVID-19 disease is being explored. Methods: A thorough literature search was performed to gather information on the pharmacological properties and toxicity of 6 drugs (azithromycin, chloroquine, favipiravir, hydroxychloroquine, lopinavir/ritonavir, remdesivir) proposed to be repurposed to treat COVID-19. Researchers emphasized affinity of these drugs to block the rapid component of the delayed rectifier cardiac potassium current (IKr) encoded by the human ether-a-go-go gene (hERG), their propensity to prolong cardiac repolarization (QT interval) and cause torsade de pointes (TdP). Risk of drug-induced Long QT Syndrome (LQTS) for these drugs was quantified by comparing six indices used to assess such risk and by querying the U.S. Food and Drug Administration (FDA) Adverse Event Reporting System database with specific key words. Data are also provided to compare the level of risk for drug-induced LQTS by these drugs to 23 other, well-recognized, torsadogenic compounds. Results: Estimators of LQTS risk levels indicated a very-high or high risk for all COVID-19 repurposed drugs except for azithromycin, although cases of TdP have been reported following the administration of this drug. There was an excellent agreement among the various indices used to assess risk of drug-induced LQTS for the six repurposed drugs and the 23 torsadogenic compounds. Conclusion: The risk-benefit assessment for the use of repurposed drugs to treat COVID-19 is complicated since benefits are currently anticipated, not proven. Mandatory monitoring of the QT interval shall be performed as such monitoring is possible for hospitalized patients or by the use of biodevices for outpatients initiated on these drugs.