Explainer: Molnupiravir, The New Antiviral Against COVID-19

What is ‘Molnupiravir’?

Molnupiravir is an investigational antiviral drug against COVID-19. Apparently, it is the first orally applied antiviral so far in the treatment of COVID-19 patients. The phase III trial results of the drug have recently been declared by its manufacturer Merck & Co. The results reveal that the drug cuts the chance of hospitalisation by 50% by reducing the progression of the disease into severe conditions among patients having mild symptoms. In its press statement, Merck said that the company will soon seek emergency use authorisation from the US regulatory agency FDA (Food and Drug Administration).

Oriol Mitjà, of the Germans Trias i Pujol University Hospital, told Science magazine, “As a researcher deeply involved on outpatient studies to treat mild COVID-19 to reduce progression and hospitalisation, the Merck announcement is to me one of the Top Biggest News Stories of the year 2021. Molnupiravir is unquestionably a game-changer! The large effect size, and the ease of administration change the paradigm of mild COVID-19 treatment with a potential to reduce COVID-19 death rates.”

Notably, the other two antiviral options that are widely used across the world are remdesivir and monoclonal antibodies. However, unlike Molnupiravir, these two antivirals are administered intravenously.

How were the Clinical Trials Conducted?

The new results came from 775 non-hospitalised patients who were involved in the study for a period of 5 days from the onset of symptoms. The patients had at least one risk factor for developing disease severity. The patients recruited for the study received a course of the drug for 5 days. This period of administering the drug was shown in lab studies to disrupt the ability of the SARS-CoV-2 virus to replicate its genome. SARS-CoV-2 is the coronavirus that causes COVID-19.

Reportedly, Merck had originally planned of including 1550 patients, which was halted by an independent data monitoring committee after it became apparent that the drug was effective.

According to the reports in the US media, the federal administration has already placed an advance order of 1.7 million doses of molnupiravir, priced at $700 per patient. The cost of the new drug, although less than the monoclonal antibodies, is far beyond acceptable for a life-saving drug, according to experts.

How Does Molnupiravir Work?

The primary way an antiviral drug function is by inhibiting the process by which a virus replicates in the host body. In the lab studies, Molnupiravir was tested on cultured cells and it was found that the drug alters critical enzymes which are necessary for the coronavirus to begin its replication (multiplication) inside the human cells.

Many of the other antiviral drugs that obey similar functions as Molnupiravir were difficult to administer as oral pills. Orally applied drugs of these kinds were found to be less effective in their action. Merck & Co. has claimed to have overcome the barrier of oral application of antiviral drugs and termed Molnupiravir as the game-changer amidst the ongoing pandemic.

Dean LI, the research and development head of Merck, said in a statement that the drug will be a ‘hammer’ against SARS-CoV-2 irrespective of the variants.

However, some experts caution that it is just the early phase and the world needs to wait for any conclusive results.

Nahid Bhadelia, the director of the Centre for Emerging Infectious Diseases Policy & Research at Boston University, told Science magazine, “Oral antivirals could have “an immense impact,” but for that to happen, rapid tests must be available so treatment can be started early in the disease course. These antivirals are not a replacement for vaccines because it is always better not to get infected in the first place.”