Remdesivir: What to know about the ‘most promising’ COVID-19 treatment

As scientists race to develop vaccines and treatments for COVID-19, there’s one drug that’s been getting a lot of attention: remdesivir. The Food and Drug Administration (FDA) has granted emergency use authorization to use it to treat the new virus.

Developed by pharmaceutical giant Gilead Sciences, remdesivir is an antiviral drug that was originally meant to fight the Ebola virus after an outbreak struck in 2013, but it was so ineffective that it was eventually shelved. However, despite its initial failures, remdesivir was later shown to be effective against both SARS and MERS, and is now being tested in new clinical trials as a potential treatment against COVID-19.

Early results from those tests have health authorities feeling “very optimistic,” in the words of Dr. Anthony Fauci. Early results of a federal study indicated remdesivir may speed the recovery of COVID-19 patients.

“It is currently the most promising antiviral drug in development for the treatment of SARS-CoV-2, the coronavirus that causes COVID-19,” Dr. Melissa Maginnis, a research scientist from the University of Maine who specializes in molecular virology and viral pathogenesis, told Digital Trends.

Here’s a quick overview of how remdesivir works, where it is on the testing timeline, and why it could be effective against the novel coronavirus.

Remdesivir vial
Ulrich Perrey / Getty

How does remdesivir work?

Like most antiviral drugs, remdesivir works by preventing the SARS-CoV-2 virus from making copies of itself. Instead of blocking viral receptors, remdesivir goes right after the heart of the virus: Its RNA and the polymerase enzyme that it uses to make copies of itself. Remdesivir is a nucleotide analog that mimics adenosine, one of the four building blocks of RNA and DNA. When a virus infects a cell and starts making copies of itself, remdesivir is slyly inserted into the viral genome instead of adenosine.

Once remdesivir’s nucleotide has inserted itself, the virus can try to make a copy of its RNA, but it won’t be able to. The presence of remdesivir stops the replication process dead in its tracks. If the coronavirus cannot multiply, its devastating respiratory effects are effectively neutralized.

Remdesivir may also have one other benefit: It likely won’t hurt the patient’s other cells because it targets just the virus.

“One of the reasons that an antiviral that specifically targets the viral polymerase is promising is because it should not have negative effects on the cell, but will shut down virus synthesis specifically,” Maginnis said.

Is remdesivir effective?

When COVID-19 exploded globally, remdesivir was dusted off and used as a last-ditch treatment for some of the first COVID-19 patients in the United States. Data from a coronavirus drug trial the National Institute of Allergy and Infectious Diseases released showed Covid-19 patients who took remdesivir usually recovered after 11 days. Those who didn’t take the drug took an average of 15 days to recover.

The first reported patient in the U.S. to contract COVID-19 was a 35-year-old man who had visited Wuhan, China. He began developing symptoms consistent with COVID-19 in early January shortly after he returned home from his trip. After six days in the hospital, his symptoms had worsened significantly, and he developed pneumonia severe enough that he required supplemental oxygen to survive. As such, the man’s doctors received permission for the compassionate use of remdesivir, and within a day, the patient’s condition improved dramatically.

Three of the first 12 patients confirmed to have COVID-19 also were treated with the compassionate use of remdesivir. All 12 patients survived, though due to the circumstances, it’s impossible to know whether the patients would’ve survived without antiviral medication or not.

A Chicago hospital that has been testing remdesivir on severe COVID-19 patients in a closely watched clinical trial has reported highly promising results, including “rapid recoveries in fever and respiratory symptoms, with nearly all patients discharged in less than a week,” according to a report from Stat News.

And a federal trial found that remdesivir may be able to treat the virus, though that data has yet to be peer-reviewed. Trump administration officials hailed the findings as a success, with President Donald Trump saying the drug proves there’s a “light at the end of the tunnel.”

What happens next?

These early cases suggest remdesivir may be a viable treatment option, but further study is needed. Clinical trials in China are already underway, but the full results of these studies haven’t been released yet.

Though the FDA has given emergency use authorization for remdesivir, the drug hasn’t been as thoroughly studied as FDA-approved drugs, and the results of the National Institute of Allergy and Infectious Diseases study have not been peer reviewed.

Even if remdesivir is approved for use, Gilead will still face production and distribution challenges, as the drug will almost certainly be in high demand. In fact, those challenges have already arisen. Gilead Sciences announced on March 23 that it was limiting remdesivir usage to its clinical trials and was curtailing compassionate use due to overwhelming demand for the drug.

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