Another malaria drug shows promise

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A new lab study finds that the antimalarial drug atovaquone can prevent the coronavirus from replicating in human lung cells. JJ van Ginkel / Getty Images
  • An antimalarial is the latest drug researchers have identified as a potential COVID-19 treatment.
  • In a laboratory study, scientists found that atovaquone inhibited the replication of SARS-CoV-2 in human lung cells.
  • The effects occurred in vitro against the Alpha, Beta and Delta variants.
  • Clinical trials are needed to see if it is possible to repeat these results in people with COVID-19.

With Omicron spreading at an alarming rate and global deaths from COVID-19 now well over 5 million, the search for effective treatments for COVID-19 is becoming increasingly urgent.

Scientists have considered many drugs, but few have realized an early promise. Even molnupiravir, hailed by many as a COVID-19 game changer, doesn’t seem to live up to the hype. In clinical trials, the actual effectiveness in preventing severe symptoms of COVID-19 is significantly lower than the initial tests suggested.

Monoclonal antibodies have some clinical benefits in preventing severe symptoms of COVID-19, but healthcare professionals should administer them intravenously. In critically ill patients on ventilators, dexamethasone, an oral steroid, can reduce deaths from COVID-19 by up to a third.

Research is therefore still ongoing for effective oral treatments that can prevent or minimize symptoms. Many researchers are testing licensed drugs that they may be able to reuse to treat or prevent COVID-19.

Now, a Danish laboratory study has published results suggesting that atovaquone has a protective effect against the coronavirus in human lung cells. Atovaquone is one of the antimalarials Malarone, which doctors have used for the treatment and prevention of malaria since 1999.

Talk to Medical News TodayDr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, Nashville, TN, praised the study: “Everyone is excited when a drug that has been used before [looks promising in the laboratory] because obviously we have a lot of clinical experience to back it up. It’s already fired. But now we have to see if it really works in people. It is a giant leap.

The study by a team from Aarhus University found that atovaquone blocked infection with the Alpha, Beta and Delta variants of COVID-19 in human lung cells in vitro.

However, Dr Schaffner urged caution: “Of course, this is a lab study. Which means it’s provocative but precocious. I hate to put it in the same category, but [I] I was just thinking of another study that looked good in the lab but fizzled out – the hydroxychloroquine study. “

The researchers started the study following anecdotal evidence from Canada that people taking Malarone appeared to have some resistance to COVID-19. Either they didn’t get the virus, or the symptoms weren’t severe if they did.

Researchers have already studied the antiviral potential of atovaquone. A 2019 study have been shown to inhibit the reproduction of Zika virus in vitro. In this study, researchers suggested that atovaquone inhibits RNA replication, thereby preventing the virus from reproducing.

Another lab study from 2020 found that the drug inhibited the fusion of Zika virus and dengue virus to host cell membranes. Viruses fuse with cell membranes to invade host cells.

Researchers have put forward several possible mechanisms for the observed effect of atovaquone on SARS-CoV-2. They suggest that it may inhibit viral replication, prevent the binding of the spike protein to the ACE2 receivers, and prevent the expression of inflammatory markers.

“I don’t want to criticize the study, but I’m not convinced it’s a huge step forward. I wish I was wrong. I would like the clinical data to show that it really does do something. Dr Jonathan Stoye, virologist at the Francis Crick Institute in London, UK, said MNT.

He added: “[What is c]What is concerning about this most recent study is that it did not find a mechanism. It sort of suggests there’s a little bit of this and a little bit of that and a little bit of something else. I do not find that very convincing.

Two small clinical trials with atovaquone are already underway. One, a stage 2 trial in Texas, ended in January this year, but the results have not been made public. This raises questions for Dr. Stoye: “I would like to see some data from this clinical trial. I just wonder what he actually showed. You would have thought if this showed anything we would have heard about it.

It is not known if the researchers are planning larger clinical trials. As Dr Schaffner commented: “Going into a clinical trial is a very, very significant investment. You have to be very convinced that something will work.

“I have reservations about the importance of this study. This is my bottom line.

– Dr Jonathan Stoye

Atovaquone may have potential, but more evidence is needed. The hunt for effective treatments for COVID-19 continues.

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