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Study: Antihistamine Diphenhydramine and Lactoferrin Have Antiviral Effects against COVID

A study by D.A. Ostrov et al titled “Highly Specific Sigma Receptor Ligands Exhibit Anti-Viral Properties in SARS-CoV-2 Infected Cells” was published 20 November 2021.

It found that the antihistamine diphenhydramine on its own as well as when combined with lactoferrin had a significant antiviral effect.

The antihistamine diphenhydramine, with on-target binding to the Histamine-1 receptor, has known off-target effects at the sigma-1 receptor [27]. Diphenhydramine was recently shown to inhibit SARS-CoV-2 infectivity and the calculated EC50 for SARS-CoV-2 by plaque reduction assay was 17.4 mg/mL (59.6 mM). This drug is safe, well-characterized, and widely available and so highly relevant in the search for COVID therapeutics.
Co-administration of 400 mg/mL of lactoferrin with diphenhydramine further reduced SARS-CoV-2 induced cytotoxicity and decreased the EC50 by 55.5% to 54.2 mg/mL (185.7 mM; Figure 8C,D). The antiviral enhancement effects of lactoferrin are more apparent at lower, therapeutically relevant concentrations of diphenhydramine (Figure 8E). Inhibition of viral replication was also investigated by qPCR (Figure 8F). Lactoferrin (400 mg/mL) was able to decrease Nprotein RNA copies by 28.0% 48 h after infection, compared to DMSO alone controls while 40 mg/mL diphenhydramine alone resulted in 32.2% reduction.

I am not saying one should stock up on Benadryl or Dimedrol, lactoferrin pills and milk, but this study is another reason to look into proven and readily available pharmaceuticals to treat so-called COVID-19 without resorting to something drastic like a vaccine.

I can just imagine lamestream media denigrating this by claiming that the cough medicine is for camels who are also conspiracy theorists and milk is only for cows who are racist Trump supporters.

And by the way, regarding ivermectin: horses breathe air too. I don’t see anyone holding their breath because of it.

Figure 8: Combinations of diphenhydramine and lactoferrin exhibit synergy against SARS-CoV-2.
Figure 8: Combinations of diphenhydramine and lactoferrin exhibit synergy against SARS-CoV-2.

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