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Clofazimine: A Promising COVID-19 Treatment

Updated: Sep 4, 2021

COVID-19 pandemic needs an immediate and effective response from everyone in the world, especially so to researchers and scientists. This is the exact thing that the experts from Sanford Burnham Prebys Medical Discovery Institute and the University of Hong Kong are doing. They are conducting thorough research on clofazimine, a leprosy drug that exhibits antiviral behaviors against SARS-CoV-2.

A Promising Candidate

An example of Clofazimine in markets (catered as leprosy drug) (source:

As per March 16, 2021, the co-senior author of this study, Sumit Chanda, Ph.D., revealed that clofazimine is a good candidate for COVID-19 treatment. It is safe, affordable, practical, can be made into pills, and able to be distributed globally. He mentioned that he and his team hope that a second phase can be conducted as soon as possible for patients that aren’t hospitalized.

Clofazimine became the chosen drug for COVID-19 treatment when a screening process was conducted to find a drug that can halt the replication of SARS-CoV-2. It was a highly throughout screening of 12.000 types of drugs, which are the drugs inside ReFRAME drug library. Chanda’s team has also reported that clofazimine is one of the 21 drugs that are effective in vitro with the amount and concentration that’s deemed safe for the human body.

In this study, the researchers tested clofazimine on hamsters that have been infected with SARS-CoV-2. The research showed that clofazimine lowered the amount of virus nested in the lungs thus minimizing lung damageand gave the same results, even more effective, when it was given prophylactically (given to the subjects prior to infection). Clofazimine was also proven to be able to prevent “cytokine storm”, an overwhelming anti-inflammatory response to SARS-CoV-2. This excessive response could be lethal to the human body. A co-senior author of this study, Ren Sun, Ph.D., said that not only clofazimine inhibited the virus, but there is also an indication that it can regulate our immune system’s response to the infection, thus mitigating the damage and suppressing inflammation.

How It Works

Clofazimine works rather effectively with its two-way action. Clofazimine begins by blocking the virus from entering the cell and then disrupts the RNA replication process that the SARS-CoV-2 needed to multiply itself. Moreover, clofazimine is also proven to be able to reduce the replication of MERS-CoV, the type of coronavirus that causes Middle East Respiratory Syndrome (MERS) that strikes lung tissues.

“Most importantly, clofazimine appears to have pan-coronavirus activity, indicating it could be an important weapon against future pandemics,” says co-senior author Kwok-Yung Yuen, M.D., the researcher who discovered that coronavirus that causes Severe Acute Respiratory Syndrome or SARS. To have pan-coronavirus activity means that clofazimine exhibited a broad spectrum of anti-CoV efficacy. He also stated that their study’s result suggests that consideration on stockpiling clofazimine should be made so it can be deployed in cases of emergencies caused by coronaviruses in the future.

Figure 1a: Clofazimine’s chemical structure.

Figure 1b: Viral copy when treatment is being given. Appears lowest on clofazimine with 10µM concentration.

Figure 1c: Virus titter when treatment is being given. Remdesivir and clofazimine pars their effect.

Figure 1d: Relative infection percentage of MERS-CoV as clofazimine inhibits the virus.

Figure 1e: MERS-CoV that infected cells were treated with and without clofazimine (uses DMSO).


Clofazimine’s Clinical Testing

Currently, clofazimine’s Phase 2 clinical testing is being conducted in Hong Kong. This testing is conducted with the combination of interferon beta-1b, an immunoregulator which is currently being used as an injection to treat people who have multiple sclerosis. Chanda mentioned that the observation data that they acquired indicated for clofazimine to be tested as a monotherapy for COVID-19 patients that makes the treatment for COVID-19 much more accessible.“People with COVID-19 would be able to simply receive a regime of low-cost pills, instead of traveling to a hospital to receive an injection,” says Chanda.

The war that wages against COVID-19 has yet to see its end. Although vaccines are the first line of defense to gain immunity to the SARS-CoV-2 virus, medication and treatment are needed for COVID-19 patients. Clofazimine presents itself to be promising both clinically and economically, so it can be one of the long-term solutions for a pandemic.



Sanford Burnham Prebys Medical Discovery Institute. 2021. Leprosy drug holds promise as at-home treatment for COVID-19. [online].ScienceDaily. Available at: <> [accessed March 26, 2021]

Yuan, S. et al. 2021. Clofazimine broadly inhibits coronaviruses including SARS-CoV-2. [online]. Nature. Available at: <> [accessed April 2 2021].

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