**2.8 Antiviral drugs**

As per the previous information related with SARS & MERS outbreak, many existing anti-viral drugs are being repurposed against SARS-CoV-2 virus in covid-19 pandemic. Remdesivir is a prodrug that converts into active metabolite and inhibits RNA dependant RNA polymerases (RdRp) thereby preventing the viral RNA synthesis [64]. It is prescribed against ebola virus infection and reported to have *in vitro* antiviral activity towards SARS and MERS coronaviruses [56]. Recently, it was reported that remdesivir prevents SARS-CoV-2 infection in human liver cancer cells [65]. Based on one clinical trial, remdesivir has been found clinically effective in 36 out of 53 patients suffered from covid-19 infection and receiving oxygen support [66]. In addition, many clinical trials are being carried out to check efficacy of remdesivir in covid-19 patients in various countries. Hung & co-workers, [67] have conducted clinical trial by using the combination of triple antiviral drug include lopinavir, ritonavir and ribavirin along with interferon which were found more promising compared to antiviral drug used alone in patient suffered from covid-19 infection. Another antiviral drug, favipiravir inhibits viral RNA polymerase enzyme and reported to have antiviral activity against many RNA viruses such as influenza, bunya and filoviruses [68]. However, to check the clinical efficacy of favipiravir in covid-19 patients various clinical trials have been performed in China and found favorable results (**Figure 1**) [13].

### **2.9 Corticosteroids**

Corticosteroids are extensively used for SARS-CoV, MERS-CoV, H1N1 influenza, and ARDS that have similar pathological features with covid-19. But, their role in reducing mortality and improving these conditions remain controversial [69]. It was reported that corticosteroids did not improve the outcome during the SARS and MERS outbreaks, but delayed viral clearance and increased rates of secondary infections [70]. A systemic review and meta-analysis are conducted in covid-19 patients by van-Paassen et al. [71], their findings based on observational and clinical studies suggested the beneficial effects of corticosteroids on mortality rate and reduced ventilation support. However, delayed viral clearance and increased secondary infection have also been observed. Similarly, the study has been conducted in China in 201 patients confirmed with covid-19 pneumonia. In 62 patients who received methylprednisolone likely had decrease risk of death [72]. As per

#### *Different Therapeutic Strategies to Tackle the Infection Associated with COVID-19 DOI: http://dx.doi.org/10.5772/intechopen.96899*

another report of Mishra & Mulani, [73] corticosteroids are not recommended in the late course of acute respiratory distress syndrome (ARDS) condition because their persistent use more than 2 weeks has increased risk of death in ARDS patients. It seems that corticosteroid treatment work like double edged sword in covid-19 fight, therefore duration of corticosteroid therapy needs to be clarified in clinical trials (**Figure 1**).
