Efforts to combat Covid-19 have advanced with the recent announcement by the United Kingdom that it has approved the first pill to treat people with Covid-19.

Molnupiravir is an antiviral medication that can be taken twice a day for five days at the onset of infection by people who are predisposed to developing severe disease, such as those who are elderly or have underlying health problems.

The UK’s Medicines and Healthcare products Regulatory Agency granted approval for the drug, which is manufactured by Merck, the US pharmaceutical giant, and Ridgeback Biotherapeutics, earlier this month (MHRA).

The National discusses the drug’s significance in relation to other Covid-19 treatments.

How efficient is it?

Trials revealed that it reduced the risk of illness requiring hospitalization by half, and the hope is that by preventing more people from becoming seriously ill, the drug will relieve pressure on already overburdened health-care systems. It could also help to reduce transmission.

“There aren’t many [drugs] approved as direct antivirals – that’s the significance of this,” said Prof Ian Jones, Professor of Virology at the University of Reading in the United Kingdom.

“The clinical trial data appeared to demonstrate a clear usefulness.” However, there is one major caveat: it must be administered early in the infection. If you’re already in the hospital, it’s not going to help.”

This means that people who are taking molnupiravir are likely to have “mild to moderate” symptoms and are vulnerable to Covid-19 due to age or underlying health conditions.

Trials in India with people with more severe illnesses revealed that the drug was ineffective at that stage, emphasizing the importance of starting it early.

“We can use it early and stop it from doing harm [before] the disease fully develops,” said Prof David Taylor, Emeritus Professor of Pharmaceutical and Public Health Policy at University College London.

“There’s every reason to believe it has a significant [contribution] in addition to vaccination and the late-stage drug treatments we already have.”

How does it function?

Molnupiravir inhibits the replication of the virus’s genetic material (ribonucleic acid or RNA), preventing the pathogen from multiplying.

It incorporates itself into the strands of RNA produced by the virus, causing mutations that eventually reduce the number of virus particles in an infected person. It has been said that it causes the virus to mutate and die.

“This is a drug that attacks virus replication, the virus’s ability to make more of itself,” Prof Jones explained.

However, the drug’s mode of action has raised concerns that it may cause mutations in human genetic material, potentially leading to tumors.

Merck said that trial data shows the drug is safe.

Molnupiravir was originally tested as a treatment for a disease in horses before interest turned to its potential effects against influenza in people.

After Covid-19 emerged, Ridgeback Therapeutics secured a licence for the drug, leading to its eventual approval for use against the coronavirus.