In vitro anti-SARS-CoV-2 activity
Nitazoxanide shows anti-SARS-CoV-2 activity in Vero E6 cells (EC50 = 2.12 μM; CC50 > 35.53 μM; SI > 16.76) and has broad activity against a range of viruses. However, activity in Vero cells does not appear sufficient to establish efficacy in vivo, as hydroxychloroquine/chloroquine have strong anti-SARS-CoV-2 activity in Vero cells but its efficacy is not well established in vivo, perhaps due to differences in TMPRSS2 expression.
Nitazoxanide may also "[potentiate] the production of type 1 interferons (alpha and beta) produced by the host’s fibroblasts," a possible mechanism of benefit in COVID-19.
Clinical trials for COVID-19
On October 23, 2020 a randomized, placebo-controlled trial of nitazoxanide in Brazil reported results (n=500):
In patients with mild Covid-19, symptom resolution did not differ between the nitazoxanide and placebo groups after 5 days of therapy. However, early nitazoxanide therapy was safe and reduced viral load significantly. --Early use of nitazoxanide in mild Covid-19 disease: randomized, placebo-controlled trial
Critiques of this trial include this twitter thread by Cardiologist Marcio S Bittencourt and that the drug may have been underdosed.
Nitazoxanide for COVID-19 research reviews
- "A Review on Possible Mechanistic Insights of Nitazoxanide for Repurposing in COVID-19"
- "Drug repurposing of nitazoxanide: can it be an effective therapy for COVID-19?"
- "Review of safety and minimum pricing of nitazoxanide for potential treatment of COVID-19"
- "Dose prediction for repurposing nitazoxanide in SARS-CoV-2 treatment or chemoprophylaxis"