Table 3.

Listed repurposed antiviral drugs in clinical development against COVID-19.

Drug/cocktail	Mode of action	Status and anti-infective mechanisms	Target diseases	References
Chloroquine	9-aminoquinolin	Status: approved, vet-approved, investigational; Mechanisms: the drug increasing endosomal pH, inhibitors of autophagy, and immunomodulating	Malaria, and autoimmune disease	(Savarino et al., 2003; Golden et al., 2015)
Remdesivir (GS-5734)	The prodrug of Nucleotide analogue	Status: experimental; Mechanisms: the drug interfering with the post-entry of virus	MERS, SARS, and Ebola	(Agostini et al., 2018; Tchesnokov et al., 2019; Lo et al., 2019)
Lopinavir/ Ritonavir	Protease inhibitors	Status: approved; Mechanisms: inhibiting the protease of HIV-1 for protein cleavage; as a result, immature or non-infectious viral particles	HIV/AIDS, MERS, and SARS	(Chu et al., 2004; Oldfield et al., 2005; Arabi et al., 2020)
Lopinavir/ritonavir, ASC09/ritonavir, with and without umifenovir	Protease inhibitors	Status: experimental, approved; Mechanisms: lopinavir/ritonavir are protease inhibitors; ASC09 is a protease inhibitor of HIV-1; Umifenovir is an entry inhibitor for influenza	HIV/AIDs, and influenza	(Harrison, 2020)
Ribavirin	Synthetic guanosine Nucleoside	Status: approved; Mechanisms: the drug interfering with the viral mRNA synthesis, also a broad-spectrum antiviral activity for both RNA and DNA	HCV, MERS, and SARS	(Chung et al., 2018; Arabi et al., 2019)
Different combinations of lopinavir/ritonavir and baloxavirmarboxil/favipiravir	Favipiravir is a guanine analog RNA-dependent RNA polymerase inhibitor, and baloxavirmarboxil is a Cap-dependent endonuclease inhibitor	Status: approved; Mechanisms: favipiravir is a guanine analog RNA-dependent RNA polymerase inhibitor, and baloxavirmarboxil is a Cap-dependent endonuclease inhibitor approved for influenza A and B	Influenza A, and B	(Harrison, 2020)
Oseltamivir	Neuraminidase inhibitor	Status: approved; Mechanisms: the drug inhibiting the viral neuraminidase activity, and also inhibiting the infectivity and viral replication	Influenza (A) viruses	(McQuade and Blair, 2015; Jefferson et al., 2014)
Oseltamivir, ritonavir/oseltamivir, ASC09/oseltamivir	Oseltamivir is a sialidase inhibitor	Status: approved; Mechanisms: oseltamivir is a sialidase inhibitor approved for influenza	Influenza	(Harrison, 2020)
Interferon α-2b alone or together with ribavirin and lopinavir/ritonavir	Interferon α-2b is a recombinant cytokine and ribavirin is a guanine derivative	Status: experimental, approved; Mechanisms: interferon α-2b is a recombinant cytokine protein with antiviral activity and ribavirin is a guanine derivative approved for viral infections	Cancer, hepatitis B, and C	(Harrison, 2020)
Ganciclovir	Nucleoside analog	Status: investigational, approved; Mechanisms: a potent inhibitor of family Herpesvirus, such as cytomegalovirus	HIV/AIDS-related cytomegalovirus infections	(Al-Badr and Ajarim, 2018)
Acyclovir/Penciclovir	Nucleoside analog	Status: approved; Mechanisms: it is a synthetic derivative of acyclic guanine, as a result of chain termination	VZV, HSV	(Chung et al., 2018)
Favipiravir (T-705)	Nucleoside analog: polymerase inhibitor of viral RNA	Status: investigational; Mechanisms: inhibiting viral reproduction by acting on its genetic copying without influencing on host cellular nucleic acid	Influenza A(H1N1), Ebola	(Shiraki, 2018; Cardile et al., 2017)
Nafamostat	Synthetic inhibitor of serine protease	Status: investigational; Mechanisms: inhibiting the membrane fusion through preventing the release of cathepsin B; role as an anticoagulant activity	MERS, Ebola, MERS, and influenza	(Hsieh and Hsu, 2007; Nishimura and Yamaya, 2015)
Azvudine	Inhibitor of reverse transcriptase	Status: experimental; Mechanisms: inhibitor of reverse transcriptase against AIDS/HIV-1	HIV-1/AIDS	(Harrison, 2020)
Nitazoxanide	Antiprotozoal agent	Status: approved, vet-approved, investigational; Mechanisms: modulating the growth, survival, and proliferation of intracellular and extracellular viruses, protozoa, bacteria (microaerophilic and anaerobic), and helminths	Human/animal coronaviruses	(Rossignol, 2014; Rossignol, 2016)
Ivermectin	Antiparasitic agent	Status: FDA-approved, vet-approved, investigational; Mechanisms: targeting the glycine receptor subunit α-3 and gamma-aminobutyric acid receptor subunit β-3 in human	Onchocerciasis, strongyloidiasis, and scabies	(Caly et al., 2020)