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Niclosamide ‐ a promising treatment for COVID‐19

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Singh, Shivani 
Weiss, Anne 
Kulkarni, Spoorthy 


Vaccines have reduced the transmission and severity of COVID-19 but there remains a paucity of efficacious treatment for drug resistant strains and more susceptible individuals, particularly those who mount a sub-optimal vaccine response, either due to underlying health conditions or concomitant therapies. Repurposing existing drugs is a timely, safe and scientifically robust method for treating pandemics such as COVID-19. Here, we review the pharmacology and scientific rationale for repurposing niclosamide, an anti-helminth already in human use as a treatment for COVID-19. In addition to potent antiviral activity, niclosamide has shown pleiotropic anti-inflammatory, antibacterial, bronchodilatory and anticancer effects in numerous pre-clinical and early clinical studies. The advantages and rationale for nebulised and intranasal formulations of niclosamide, which target the site of primary infection in COVID-19, are reviewed. Finally, we provide an overview of ongoing clinical trials investigating niclosamide as a promising candidate against SARS-CoV-2.


Funder: Evelo Biosciences

Funder: AstraZeneca; Id:

Funder: UNION Therapeutics, Denmark

Funder: Kidney Research UK; Id:

Funder: Addenbrooke's Charitable Trust, Cambridge University Hospitals; Id:

Funder: LifeArc; Id:


COVID-19, clinical trials, niclosamide, repurposing, Antiviral Agents, Drug Repositioning, Humans, Niclosamide, Pandemics, SARS-CoV-2, COVID-19 Drug Treatment

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British Journal of Pharmacology

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National Institute for Health and Care Research (IS-BRC-1215-20014)
The PROTECT-V trial is overseen by the NIHR Covid-19 Understanding and Elimination-Trials Implementation Panel (CUE-TIP). PROTECT-V is funded by LifeArc, Addenbrooke’s Charitable Trust and Kidney Research UK with financial contributions from Union Therapeutics for the niclosamide arm. The TACTIC-E trial is funded by UNION Therapeutics, Denmark as well as AstraZeneca and Evelo Biosciences with significant financial support from the NIHR Cambridge BRC. RS and JC acknowledge funding support from the Cambridge NIHR BRC. MS is a shareholder of UNION Therapeutics and AW benefits from an employee incentive scheme. AW and MS also acknowledge support from Innovation Fund Denmark under grant number 0153-00209 and The Novo Nordisk Foundation under NFF grant number NNF20CC0035580, respectively.