- In an effort to fight SARS-CoV-2, and with the likely rise of other coronaviruses, experts are looking for existing drugs that can fight these infections.
- A leprosy drug called clofazimine has shown promise against SARS-CoV-2 in hamsters.
- Clofazimine blocks the ability of SARS-CoV-2 to enter cells and replicate via RNA.
- The drug has also shown promise against Middle East Respiratory Syndrome (MERS) in laboratory experiments.
SARS-CoV-2, which is the virus responsible for COVID-19, is not the only zoonotic coronavirus. In fact, it is the third to have seen the light of day since the turn of the century. It was preceded by Severe Respiratory Syndrome (SARS) in 2003 and MERS in 2012.
There will likely be more coronavirus if the recent past is any indication. However, there are currently not many drugs that can effectively combat them.
Researchers rushed to identify existing drugs that could be helpful in this fight, with a team last year identifying 21 existing drugs as showing promise. Among these was a leprosy drug called clofazimine, which has been shown to be effective against SARS and MERS in laboratory experiments.
A new study by researchers at the Sanford Burnham Prebys Medical Discovery Institute in San Diego, Calif. And the University of Hong Kong at Pok Fu Lam suggests that it may also be useful in the treatment of COVID-19.
Clofazimine exhibits antiviral properties against SARS-CoV-2 and limits the extreme inflammatory response that commonly occurs with COVID-19.
The study has been peer reviewed and will soon appear in edited form in the journal Nature.
The Food and Drug Administration (FDA) has already approved its use against leprosy and is on the World Health Organization (WHO) Model List of Essential Medicines. Experts have carefully checked the drug’s safety, although it is not currently available for sale in the United States.
Study co-lead author Dr Sumit K. Chanda – from the Immunity and Pathogenesis Program at Sanford Burnham Prebys – says: “Clofazimine is an ideal candidate for COVID-19 treatment. It is safe, affordable, easy to manufacture, taken in pill form, and can be made available worldwide. ”
Dr Chanda explains, “We hope to test clofazimine in a Phase 2 clinical trial as soon as possible for people who test positive for COVID-19 but are not hospitalized,” adding:
“Since there is currently no outpatient treatment available for these people, clofazimine may help reduce the impact of the disease, which is especially important now that we are seeing new variants of the virus emerging and against which vaccines current ones seem less effective. ”
In the study, researchers administered clofazimine to hamsters with SARS-CoV-2 and prophylactically (preventively) to other hamsters that did not yet have the virus.
The two groups the researchers treated with clofazimine had less SARS-CoV-2 in their lungs after taking the drug.
Clofazimine also prevented the often fatal inflammatory overreaction that commonly occurs in humans. This is called the “cytokine storm”.
Study co-lead author Dr Ren Sun of the University of Hong Kong reports: “Animals that received clofazimine had less lung damage and lower viral loads, especially when they were given clofazimine. were receiving the drug before infection.
Dr Sun adds, “In addition to inhibiting the virus, there are indications that the drug also regulates the host’s response to the virus, which allows for better control of infection and inflammation.”
The study suggests that clofazimine fights SARS-CoV-2 by doing two things: blocking the entry of the virus into cells and disrupting the virus’s RNA replication.
The researchers also found that clofazimine, when administered to hamsters, worked synergistically with remdesivir. It is the most common drug currently used as a COVID-19 treatment.
Since clofazimine is affordable and easy to manufacture, it can help stretch the limited – and comparatively expensive – supply of remdesivir.
Given the concerns of experts about future coronaviruses, it is equally exciting that clofazimine appears to prevent MERS from replicating in vitro in human lung tissue.
“More importantly, clofazimine appears to have pan-coronavirus activity, which indicates [that] it could be an important weapon against future pandemics, ”says study lead co-author Dr Kwok-Yung Yuen of Infectious Diseases at the University of Hong Kong.
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