Drug repurposing in COVID-19: A review with past, present and future

The coronavirus SARS-CoV-2 which causes the COVID-19 disease is a global public health emergency. Coronavirus are single-stranded positive-sense RNA viruses and their genome size is approximately 30 kb, which encodes some important structural proteins. The interaction between viral Spike protein and ACE2 on the host cell surface is of significant interest since it initiates the infection process. This review will focus on the effectiveness of reuse of currently used drugs against COVID-19, including clinical trials, molecular docking, and computational modelling approach. METHODS: A systematic search in Pubmed, MEDLINE, EMBASE was conducted from from January 2020 to July 2021. Applying computational, clinical and experimental approaches, numerous drugs such as remdesivir, favipiravir, ribavirin, lopinavir, ritonavir, tocilizumab have been repurposed and have shown promising protection against SARS-CoV2 both in vitro and in clinical conditions. Although there is only one repurposed drug approved by the U.S. Food and Drug Administration (FDA) to treat coronavirus disease 2019 (COVID-19), i.e, Remdesivir. However, the FDA withdrew the authorization of the drugs Hydroxychloroquine and chloroquine,that are not effective for COVID-19 and can also cause serious heart problems. Molecular coupling would be the ideal technique to identify such therapeutic agents against COVID19.