Nitazoxanide shows anti-SARS-CoV-2 activity in Vero E6 cells. From "Remdesivir and chloroquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitro". Photo CC-BY Wang, M., Cao, R., Zhang, L. et al.

Nitazoxanide, a broad-spectrum antiparasitic, has been proposed as a possible COVID-19 therapeutic.

In vitro anti-SARS-CoV-2 activity

Nitazoxanide shows anti-SARS-CoV-2 activity in Vero E6 cells and has broad activity against a range of viruses.  However, activity in Vero cells does not appear sufficient to establish effiacy in vivo, as hydroxychloroquine/chloroquine have strong anti-SARS-CoV-2 activity in Vero cells but fail in vivo, perhaps due to differences in TMPRSS2 expression.

Nitazoxnide 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:

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

See also