Drug Repurposing for COVID-19: Current Status of Potential Therapeutics

The maneuver clinical investigation of an effective drug for coronavirus disease 2019 (COVID-19) is still ongoing and the milieu of a successful investigational drug with proven efficacy is still obscure. Drug repurposing is a method to identify new therapeutic uses for existing drugs, which include approved, delayed, withdrawn, and investigational drugs and drug candidates. Indeed, the cost of the standard drug discovery and development process amounts to more than a billion dollars, and the investigations are expected to last 10–15 years. Notably, repurposing existing approved drugs is a potential, effective, and profitable approach as it significantly reduces the cost and time of developing a new drug. Owing to the established safety, pharmacokinetic, and pharmacodynamic profiles of potential drug candidates, drug repurposing may allow scientists to skip or shorten some critical steps of the traditional drug discovery and development process. Prospectively, advanced approaches could be harnessed to conduct proof-of-concept trials that would accelerate the clinical evaluation of repurposed drugs. Drawing lessons from repurposing efforts for COVID-19 therapeutics, the present review briefly summarizes the current status of various potential drugs that have been clinically evaluated for repurposing platforms as well as that could maximize safety, efficacy, and possible therapeutic benefits, both alone or in combination, and clinical outcomes in patients with COVID-19.