4c . The historical safety of the proposed repurposed drug.
We need to know the historical safety of proposed RAS inhibitors in exploring their potential role as repurposed drugs for treating COVID-19. Losartan, telmisartan, olmesartan (and additional AT1R antagonists) have been widely applied in the clinic since the 1990s for control of hypertension, diabetes and some kidney disorders, and are known as safe drugs that are rarely implicated in adverse drugs events (54-55).
Based on historical safety experience data there would be an argument to explore further the possibility of a new indication for RAS inhibitors as repurposed drugs in COVID-19.