- Experts are looking for existing drugs that can fight SARS-CoV-2 and other coronaviruses in order to combat SARS-CoV-2 and the likely rise of other coronaviruses.
- Clofazimine, a leprosy drug, has shown promise in hamsters against SARS-CoV-2.
- Clofazimine prevents SARS-CoV-2 from entering cells and replicating via RNA.
- In laboratory tests, the drug showed promise against Middle East respiratory syndrome (MERS).
The virus that causes COVID-19, SARS-CoV-2, is not the only zoonotic coronavirus. It is, in fact, the third to emerge since the turn of the century. SARS (severe acute respiratory syndrome) in 2003 and MERS (measles, encephalitis, and rhinitis) in 2012 preceded it.
If the recent past is any indication, there will be more coronaviruses. However, there aren’t many drugs on the market that can effectively combat them right now.
Researchers have been racing to find existing drugs that could help in this fight, with one team identifying 21 drugs that showed promise last year. One of these was clofazimine, a leprosy drug that has been shown to be effective against both SARS and MERS in laboratory tests.
According to new research from the Sanford Burnham Prebys Medical Discovery Institute in San Diego, CA, and the University of Hong Kong in Pok Fu Lam, it could also help treat COVID-19.
Clofazimine has antiviral properties against SARS-CoV-2 and helps to control the severe inflammatory response that COVID-19 causes.
The study has gone through peer review and will be published in Nature in edited form soon.
A well-known and risk-free drug
Experts could use clofazimine against SARS-CoV-2 and COVID-19 right away if researchers confirm the drug’s efficacy.
It has already been approved by the Food and Drug Administration (FDA) for use against leprosy, and it is included in the World Health Organization’s (WHO) Model List of Essential Medicines. Though the drug has been thoroughly vetted for safety, it is not currently available for purchase in the United States.
“Clofazimine is an ideal candidate for a COVID-19 treatment,” says co-senior study author Dr. Sumit K. Chanda of Sanford Burnham Prebys’ Immunity and Pathogenesis Program. It is safe, inexpensive, simple to make, can be taken as a pill, and can be made widely available.”
“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,” Dr. Chanda says, adding, “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.”
“Since there is currently no outpatient treatment available for these individuals, clofazimine may help reduce the impact of the disease, which is particularly important now as we see new variants of the virus emerge and against which the current vaccines appear less efficacious.”
Clofazimine’s side effects
The researchers gave clofazimine to hamsters with SARS-CoV-2 and prophylactically (preventively) to hamsters who had not yet been exposed to the virus in the study.
After taking clofazimine, the researchers found that both groups had less SARS-CoV-2 in their lungs.
Clofazimine also prevented the potentially fatal inflammatory overreaction seen in humans. This is referred to as a “cytokine storm.”
“The animals that received clofazimine had less lung damage and lower viral load, especially when receiving the drug before infection,” says co-senior study author Dr. Ren Sun of the University of Hong Kong.
“Aside from inhibiting the virus, there are indications that the drug also regulates the host response to the virus, allowing for better control of infection and inflammation,” says Dr. Sun.
Clofazimine, according to the study, fights SARS-CoV-2 by blocking the virus’s entry into cells and disrupting the virus’s RNA replication.
A partner for remdesivir and more
When given to hamsters, the researchers discovered that clofazimine had a synergistic effect with remdesivir. This is the most widely prescribed COVID-19 treatment at the moment.
Because clofazimine is cheap and simple to make, it could help stretch the supply of remdesivir, which is limited and relatively expensive.
Given experts’ concerns about future coronaviruses, the discovery that clofazimine appears to prevent MERS replication in human lung tissue in vitro is equally exciting.
Dr. Kwok-Yung Yuen of the University of Hong Kong’s Department of Infectious Diseases says, “Potentially most importantly, clofazimine appears to have pan-coronavirus activity, indicating [that] it could be an important weapon against future pandemics.”