Favipiravir and Ivermectin Showed in Vitro Synergistic Antiviral Activity against SARS-CoV-2
et al., Research Square, doi:10.21203/rs.3.rs-941811/v1, Oct 2021
Ivermectin for COVID-19
4th treatment shown to reduce risk in
August 2020, now with p < 0.00000000001 from 106 studies, recognized in 24 countries.
No treatment is 100% effective. Protocols
combine treatments.
6,300+ studies for
210+ treatments. c19early.org
|
In vitro study showing a strong synergistic effect of ivermectin and favipiravir. Combining multiple antiviral drugs with different mechanisms of action helps to minimize drug resistance and toxicity.
For ivermectin alone, IC50 for Calu-3 was 0.2µM, supporting in vivo efficacy at 0.6 mg/kg.
74 preclinical studies support the efficacy of ivermectin for COVID-19:
Ivermectin, better known for antiparasitic activity, is a broad spectrum antiviral with activity against many viruses including H7N771, Dengue37,72,73 , HIV-173, Simian virus 4074, Zika37,75,76 , West Nile76, Yellow Fever77,78, Japanese encephalitis77, Chikungunya78, Semliki Forest virus78, Human papillomavirus57, Epstein-Barr57, BK Polyomavirus79, and Sindbis virus78.
Ivermectin inhibits importin-α/β-dependent nuclear import of viral proteins71,73,74,80 , shows spike-ACE2 disruption at 1nM with microfluidic diffusional sizing38, binds to glycan sites on the SARS-CoV-2 spike protein preventing interaction with blood and epithelial cells and inhibiting hemagglutination41,81, shows dose-dependent inhibition of wildtype and omicron variants36, exhibits dose-dependent inhibition of lung injury61,66, may inhibit SARS-CoV-2 via IMPase inhibition37, may inhibit SARS-CoV-2 induced formation of fibrin clots resistant to degradation9, inhibits SARS-CoV-2 3CLpro54, may inhibit SARS-CoV-2 RdRp activity28, may minimize viral myocarditis by inhibiting NF-κB/p65-mediated inflammation in macrophages60, may be beneficial for COVID-19 ARDS by blocking GSDMD and NET formation82, may interfere with SARS-CoV-2's immune evasion via ORF8 binding4, may inhibit SARS-CoV-2 by disrupting CD147 interaction83-86, shows protection against inflammation, cytokine storm, and mortality in an LPS mouse model sharing key pathological features of severe COVID-1959,87, may be beneficial in severe COVID-19 by binding IGF1 to inhibit the promotion of inflammation, fibrosis, and cell proliferation that leads to lung damage8, may minimize SARS-CoV-2 induced cardiac damage40,48, may counter immune evasion by inhibiting NSP15-TBK1/KPNA1 interaction and restoring IRF3 activation88, may disrupt SARS-CoV-2 N and ORF6 protein nuclear transport and their suppression of host interferon responses1, reduces TAZ/YAP nuclear import, relieving SARS-CoV-2-driven suppression of IRF3 and NF-κB antiviral pathways35, increases Bifidobacteria which play a key role in the immune system89, has immunomodulatory51 and anti-inflammatory70,90 properties, and has an extensive and very positive safety profile91.
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Jitobaom et al., 14 Oct 2021, preprint, 8 authors.
In vitro studies are an important part of preclinical research, however results may be very different in vivo.
Favipiravir and Ivermectin Showed in Vitro Synergistic Antiviral Activity against SARS-CoV-2
doi:10.21203/rs.3.rs-941811/v1
Despite the urgent need for effective antivirals against SARS-CoV-2 to mitigate the catastrophic impact of the COVID-19 pandemic, there are still no proven effective and widely available antivirals for COVID-19 treatment. Favipiravir and Ivermectin are among common repurposed drugs, which have been provisionally used in some countries. There have been clinical trials with mixed results, and therefore, it is still inconclusive whether they are effective or should be dismissed. It is plausible that the lack of clearcut clinical bene ts was due to the nding of only marginal levels of in vivo antiviral activity. An obvious way to improve the activity of antivirals is to use them in synergistic combinations. Here we show that Favipiravir and Ivermectin had the synergistic effects against SARS-CoV-2 in Vero cells. The combination may provide better e cacy in COVID-19 treatment. In addition, we found that Favipiravir had an additive effect with Niclosamide, another repurposed anti-parasitic drug with anti-SARS-CoV-2 activity. However, the anti-SARS-CoV-2 activity of Favipiravir was drastically reduced when tested in Calu-3 cells. This suggested that this cell type might not be able to metabolize Favipiravir into its active form, and that this de ciency in some cell types may affect in vivo e cacy of this drug.
Vero E6 cells were seeded in 12-well plates at a density of 2.2×10 5 cells/well, which allowed 100% con uence to be reached within 18 hr. The culture medium was removed, and the cells were inoculated with 100µl of 10-fold serial dilutions of virus supernatants for 1 hr. at 37 o C with 5%CO 2 . After that, the virus supernatants were removed, and the cells were overlaid with 1.56% microcrystalline cellulose (Avicel, RC-591) in 2%FBS-MEM. The cells were further incubated in the standard condition for three days. The overlaid medium was removed, and the cells were xed with 10% (v/v) formalin in phosphatebuffered saline (PBS) for 2 hr. The xed infected cells were washed in tap water, stained with 1% (w/v) crystal violet in 20% (v/v) ethanol for 5 min and washed to remove the excess dyes. The plaques were counted, and the viral titers were calculated in plaque forming units per ml (pfu/ml). 50% cell culture infectious dose (TCID 50 ) endpoint dilution assay Vero E6 cells were seeded in 96-well plates at a density of 3×10 4 cells/well. The culture medium was removed, and the cells were incubated with half-log10 serial dilution of the virus stock for 48 hr. at 37 o C with 5%CO 2 . After that, the cells were xed with 1:1 methanol/acetone for 30 min at 4 o C and the infectivity was detected with an antibody against the SARS-CoV-2 nucleocapsid protein (40143-R001, Sino Biological). The viral TCID 50 titers were calculated using the Reed and Muench method 73 .
One-step qRT-PCR for..
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DOI record:
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"abstract": "<jats:title>Abstract</jats:title>\n <jats:p>Despite the urgent need for effective antivirals against SARS-CoV-2 to mitigate the catastrophic impact of the COVID-19 pandemic, there are still no proven effective and widely available antivirals for COVID-19 treatment. Favipiravir and Ivermectin are among common repurposed drugs, which have been provisionally used in some countries. There have been clinical trials with mixed results, and therefore, it is still inconclusive whether they are effective or should be dismissed. It is plausible that the lack of clear-cut clinical benefits was due to the finding of only marginal levels of <jats:italic>in vivo</jats:italic> antiviral activity. An obvious way to improve the activity of antivirals is to use them in synergistic combinations. Here we show that Favipiravir and Ivermectin had the synergistic effects against SARS-CoV-2 in Vero cells. The combination may provide better efficacy in COVID-19 treatment. In addition, we found that Favipiravir had an additive effect with Niclosamide, another repurposed anti-parasitic drug with anti-SARS-CoV-2 activity. However, the anti-SARS-CoV-2 activity of Favipiravir was drastically reduced when tested in Calu-3 cells. This suggested that this cell type might not be able to metabolize Favipiravir into its active form, and that this deficiency in some cell types may affect <jats:italic>in vivo</jats:italic> efficacy of this drug.</jats:p>",
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