1.1 Pathogenesis of COVID-19
Clinically, COVID-19 is characterized by fever, cough, myalgia and dyspnoea, sometimes evolving into fulminant respiratory failure. Though the pathogenic mechanisms are diverse, there are two major processes that lead to the morbidity and mortality of this disease: initially the viral infection, followed by a host inflammatory response that frequently results in excessive secretion of inflammatory cytokines (e.g. IL-2, IL-6, IL-8, IL-10 and TNFα). This immune response can develop into a self-targeting toxic “cytokine storm” in which the lungs fill with inflammatory secretions causing critical damage to pulmonary tissue. Accordingly, the development of therapeutics for COVID-19 can be divided into two groups: anti-viral and anti-inflammatory. Even though the search for a vaccine and anti-viral agents has already been initiated, the de novo development of a safe, COVID-19 specific solution and its worldwide distribution may take several years; regrettably, the need for a therapeutic that is available immediately is growing daily. Therefore, repurposing an already approved drug may offer a promising approach to address this urgent need.