New Delhi: The experimental drug remdesivir was thrust in the spotlight Wednesday after top US physician and government adviser Dr Anthony Fauci recommended its use to treat Covid-19 patients.
“What it has proven is that a drug can block this virus,” said Fauci, the director of the US National Institute of Allergy and Infectious Diseases (NIAID), referring to data from a study of more than 1,000 patients across the US and around the world.
Fauci said preliminary results had shown that the drug led to faster recovery in Covid-19 patients. He said there were indications the drug led to fewer deaths, but added that this part of the analysis is still under review.
Three other trials have been conducted to test the efficacy of remdesivir for Covid-19 treatment.
The first study after a trial was published earlier this month in the New England Journal of Medicine, which recommended “compassionate use” of the drug.
The second conducted in China and published in The Lancet Wednesday concluded that the drug did not have any significant effects on critically ill patients and the third — a larger study — published the same day by Gilead Sciences showed positive results in the third phase of the trial.
ThePrint takes a look at what this drug is and how it works to treat Covid-19 patients.
What is Remdesivir?
Remdesivir is an experimental antiviral drug that was developed by US pharmaceutical company Gilead Sciences first for Hepatitis C and then as a potential treatment for Ebola and Marburg virus infections. The drug was rapidly pushed through clinical trials after the 2013-16 Ebola epidemic in West Africa.
The drug was one among four therapies, which underwent clinical trials in the Democratic Republic of Congo in 2018.
The other three therapies were two cocktails of monoclonal antibodies, which are made by identical immune cells that blunt the spread of the virus, and a ZMapp drug by Mapp Biopharmaceutical.
The clinical trials involving 700 patients were conducted by the NIAID in collaboration with the National Institute for Biomedical Research, Congo’s Ministry of Health and the World Health Organisation.
Eleven months later, in August 2019, Congolese officials announced that the treatment with monoclonal antibodies had proved to be more effective.
At the time, Dr Fauci had announced that 33 per cent of those who had received the remdesivir had died, while only 6 per cent of those who got Regeneron drug died, and only 11 per cent of those who got the Biotherapeutics drug died. These two drugs were the cocktails of monoclonal antibodies.
Remdesivir made a revival in January this year as a treatment for Covid-19 as it had shown promising results in blocking Severe Acute Respiratory Syndrome (SARS) and the Middle East Respiratory Syndrome (MERS).
The trials, however, have only been conducted on animals so far.
How does the drug work?
After infecting the host cell, the SARS-CoV-2 virus strain, which causes the Covid-19 infection, produces “viral polyproteins”.
Essentially, these polyproteins are needed for the virus to replicate the viral genome. These viral polyproteins lead to the formation of “multisubunit complex”, which are “protein” chains that contain enzymatic activities.
The genetic matter of the virus is based on a single-stranded ribo-nucleic acid or RNA and so these enzymatic activities spur the replication of this RNA in a process called the RNA-dependent polymerases.
The RNA-polymerase accepts nucleotides, which become building blocks of RNA.
Remdesivir works by mimicking one of the four building blocks, adenosine (a nucleoside), which then inhibits the virus’ replication.
So, when the virus infects a cell and starts making copies of itself, remdesivir is inserted into the virus’s genome instead of adenosine.