Current status of therapeutic alternatives for COVID-19: A narrative review

Since December 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has exploded and led to a global crisis. Currently, the global case numbers topped 200 million, and toll of dead exceeded 4 million around the world. The pathogenesis of coronavirus disease 2019 (COVID-19) is driven by two processes. During the first stage of the infection that lasts around 5-7 days, replication of SARS-CoV-2 occurs. In the second stage, the disease may progress due to an exaggerated inflammatory response leading to tissue damage. Therefore, it is anticipated that antiviral agents would be effective during the early phase of the disease, while immunomodulator agents are likely to be more beneficial in the second stage of COVID-19. This basic concept of disease development led to explore several antiviral and immunomodulator agents for the treatment of COVID-19. Currently, remdesivir is the only available Food and Drug Administration-approved antiviral agent for the treatment of COVID-19. However, some other agents have been approved by various mechanisms, including Emergency Use Authorizations, Emergency Investigational New Drug applications, compassionate use or expanded access programs. In addition, a variety of repurposed agents that were approved for other indications are being investigated for the treatment of COVID- 19 in clinical trials. A myriad of publications including randomized controlled trials (RCTs) are emerging continuously and are accessible as peer-reviewed, pre-print and press release formats. Considering the critical importance of RCTs in generating evidence and providing further guidance on COVID-19 treatment, we herein reviewed only RCTs and meta-analyses. The discussion includes antiviral agents (hydroxychloroquine, lopinavir/ritonavir, remdesivir, favipiravir and ivermectin) and, various immunomodulatory drugs (corticosteroids, tocilizumab, baricitinib, and IL-1 inhibitors). Other investigational therapies including darunavir/cobicistat, umifenovir, sofosbuvir/daclatasvir, sofobuvir/ledipasvir, ribavirin, nitazoxanide and interferon-based regimens were not evaluated due to insufficient data on the efficacy and safety of these agents.