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Health Guide / COVID-19

Molnupiravir: an oral treatment for COVID-19?

yael coopermangina-allegretti

Reviewed by Yael Cooperman, MD, written by Gina Allegretti, MD

Last updated: Feb 09, 2022
6 min read

table of contents

  1. What is molnupiravir? 
  2. How effective is molnupiravir at treating COVID? 
  3. Advantages of molnupiravir 
  4. Disadvantages of molnupiravir
  5. Molnupiravir side effects
  6. Where can you get molnupiravir? 

Important

Information about the novel coronavirus (the virus that causes COVID-19) is constantly evolving. We will refresh our novel coronavirus content periodically based on newly published peer-reviewed findings to which we have access. For the most reliable and up-to-date information, please visit the CDC website or the WHO’s advice for the public.

Since the beginning of the coronavirus pandemic, researchers have been focused on finding ways to prevent and treat COVID-19. The availability of COVID vaccines was a big step towards prevention. 

But if you got infected, there weren’t always many options for treatment. Most COVID-19 drugs (like monoclonal antibodies and the antiviral drug, remdesivir) are IV medications reserved for hospitalized patients with severe illness.  

But oral drugs like molnupiravir may offer a treatment solution to reduce the risk of severe disease among people who don’t need hospitalization. Molnupiravir has received emergency use authorization (EUA) from the U.S. Food and Drug Administration (FDA) for the treatment of mild to moderate COVID in people at high risk for developing severe COVID-19 (Merck, 2021-c).

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What is molnupiravir? 

Molnupiravir was first studied as a medication to treat viruses like influenza. However, researchers discovered that it works against other viruses too––including coronavirus (Imran, 2021). The medication works by attacking the virus’s genetic material, preventing it from making more copies of itself (Willyard, 2021; Mendez-Arias, 2021). 

What makes molnupiravir different from other available COVID treatments? The biggest difference is that it’s available in pill form. This opens the door to new possibilities, like treating COVID at home instead of at the hospital. Molnupiravir is sold under the brand names Lagevrio and Molulife.

How effective is molnupiravir at treating COVID? 

Evidence suggests that molnupiravir effectively treats mild to moderate COVID and lowers the risk of hospitalization and death.  

In one clinical trial, people infected with the coronavirus were treated either with molnupiravir or a placebo. After 29 days, 7% of people in the molnupiravir group were hospitalized compared to almost twice as many in the placebo group. There were nine deaths in the placebo group and only one in the molnupiravir group. The study concluded that molnupiravir lowered the risk of hospitalization and death from COVID significantly (Jayk Bernal, 2021). 

In another trial, researchers gave people either molnupiravir or a placebo in the first seven days they showed symptoms. They found that after just four days of treatment, the virus was no longer detectable among any of the participants who took molnupiravir. 

Even though they were treated early, the molnupiravir group still developed protective antibodies within a month of being infected, which indicated that they still might get long-term protection from the virus. This study is not yet peer-reviewed, but the results are encouraging (Fischer, 2021).

Does molnupiravir work against new COVID variants? 

In clinical trials, molnupiravir was equally effective against different strains of the virus, including newer variants like Delta, Mu, and Omicron (Merck, 2021-c; Vangeel, 2021). 

Advantages of molnupiravir 

One of the biggest draws of molnupiravir is that it can be taken by mouth, meaning you don’t necessarily need to be in a hospital to get it. It’s most effective for mild to moderate COVID and can stop symptoms before severe disease sets in, keeping you out of the hospital entirely.

Disadvantages of molnupiravir

When you’re treating an infection, timing is everything. And that’s definitely the case with some antivirals. For example, if you’ve ever taken Tamiflu (also known as oseltamivir) for the flu, you know it has to be taken within the first few days of symptoms for it to work. 

The same is true for molnupiravir. You need to take the medication within five days of symptom onset for it to be effective. There’s no evidence from clinical trials showing any benefit to this drug for advanced or severe disease (Gupta, 2021; Willyard, 2021). 

Since the medication when symptoms first appear, getting the drug distributed to all of the people who come down with COVID is complicated. This is why treatment is mostly focused on people at high-risk of developing severe COVID.

Molnupiravir side effects

Most people who take molnupiravir don’t have many side effects and the ones that occur are usually mild. The incidence of side effects in clinical trials was similar in the treatment and placebo groups. Common side effects include headache, nausea, runny nose, and insomnia (Painter, 2021; Fischer, 2021). 

Where can you get molnupiravir? 

Currently, molnupiravir has EUA in the United States and full authorization in the United Kingdom for COVID treatment in people at high-risk for developing severe disease. Risk factors include people with a history of heart disease, diabetes, or obesity (Merck, 2021-b; Gov.UK, 2021). 

A COVID-19 pill that’s taken at home, keeps you out of the hospital, and prevents severe disease and death is one more tool in our arsenal when it comes to fighting the pandemic. While the drug may not be widely available in the United States, if you’re at high risk of developing severe COVID you may be a candidate for it if you catch the coronavirus. 

In the meantime, the best way to protect yourself from COVID is getting vaccinated, making sure to get a booster shot, and following guidelines regarding handwashing and social distancing. 

References

  1. Fischer, W., Eron, J. J., Holman, W., Cohen, M. S., Fang, L., Szewczyk, L. J., et al. (2021). Molnupiravir, an Oral Antiviral Treatment for COVID-19. medRxiv: The Preprint Server for Health Sciences. doi:10.1101/2021.06.17.21258639. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8219109/   
  2. Gordon, C. J., Tchesnokov, E. P., Schinazi, R. F., & Götte, M. (2021). Molnupiravir promotes SARS-CoV-2 mutagenesis via the RNA template. The Journal of Biological Chemistry, 297(1). doi:10.1016/j.jbc.2021.100770. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8110631/
  3. Gov.UK. (2021). First oral antiviral for COVID-19, Lagevrio (molnupiravir), approved by MHRA. Retrieved on Nov. 15, 2021 from https://www.gov.uk/government/news/first-oral-antiviral-for-covid-19-lagevrio-molnupiravir-approved-by-mhra
  4. Imran, M., Kumar Arora, M., Asdaq, S., Khan, S. A., Alaqel, S. I., Alshammari, M. K., et al. (2021). Discovery, Development, and Patent Trends on Molnupiravir: A Prospective Oral Treatment for COVID-19. Molecules, 26(19), 5795. doi:10.3390/molecules26195795. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8510125/
  5. Jayk Bernal, A., Gomes da Silva, M. M., Musungaie, D. B., Kovalchuk, E., Gonzalez, A., Delos Reyes, V., et al. (2022). Molnupiravir for Oral Treatment of Covid-19 in Nonhospitalized Patients. The New England Journal of Medicine, 386(6), 509–520. doi:10.1056/NEJMoa2116044. Retrieved from https://www.nejm.org/doi/full/10.1056/NEJMoa2116044 
  6. Menéndez-Arias, L. (2021). Decoding molnupiravir-induced mutagenesis in SARS-CoV-2. The Journal of Biological Chemistry, 297(1), 100867. doi:10.1016/j.jbc.2021.100867. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8188802/ 
  7. Merck-a. (2021). Merck and Ridgeback’s Investigational Oral Antiviral Molnupiravir Reduced the Risk of Hospitalization or Death by Approximately 50 Percent Compared to Placebo for Patients with Mild or Moderate COVID-19 in Positive Interim Analysis of Phase 3 Study. Retrieved on Nov. 5, 2021 from https://www.merck.com/news/merck-and-ridgebacks-investigational-oral-antiviral-molnupiravir-reduced-the-risk-of-hospitalization-or-death-by-approximately-50-percent-compared-to-placebo-for-patients-with-mild-or-moderat/
  8. Merck-b. (2021). Merck and Ridgeback’s Molnupiravir, an Oral COVID-19 Antiviral Medicine, Receives First Authorization in the World. Retrieved on Nov. 15, 2021 from https://www.merck.com/news/merck-and-ridgebacks-molnupiravir-an-oral-covid-19-antiviral-medicine-receives-first-authorization-in-the-world/
  9. Merck-c. (2021). Merck and Ridgeback’s Molnupiravir Receives U.S. FDA Emergency Use Authorization for the Treatment of High-Risk Adults With Mild to Moderate COVID-19. Retrieved on Jan. 14, 2022 from https://www.merck.com/news/merck-and-ridgebacks-molnupiravir-receives-u-s-fda-emergency-use-authorization-for-the-treatment-of-high-risk-adults-with-mild-to-moderate-covid-19/
  10. Painter, W. P., Holman, W., Bush, J. A., Almazedi, F., Malik, H., Eraut, N., et al. (2021). Human Safety, Tolerability, and Pharmacokinetics of Molnupiravir, a Novel Broad-Spectrum Oral Antiviral Agent with Activity Against SARS-CoV-2. Antimicrobial Agents and Chemotherapy, 65(5), e02428-20. doi:10.1128/AAC.02428-20. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8092915/
  11. Painter, G. R., Natchus, M. G., Cohen, O., Holman, W., & Painter, W. P. (2021). Developing a direct acting, orally available antiviral agent in a pandemic: the evolution of molnupiravir as a potential treatment for COVID-19. Current Opinion in Virology, 50, 17–22. doi:10.1016/j.coviro.2021.06.003. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8277160/
  12. Singh, A. K., Singh, A., Singh, R., & Misra, A. (2021). Molnupiravir in COVID-19: A systematic review of literature. Diabetes & Metabolic Syndrome, 15(6), 102329. doi:10.1016/j.dsx.2021.102329. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8556684/
  13. U.S. Food and Drug Administration (FDA-a). (2021). FDA to Hold Advisory Committee Meeting to Discuss Merck and Ridgeback’s EUA Application for COVID-19 Oral Treatment. Retrieved on Nov. 15, 2021 from https://www.fda.gov/news-events/press-announcements/fda-hold-advisory-committee-meeting-discuss-merck-and-ridgebacks-eua-application-covid-19-oral
  14. U.S. Food and Drug Administration (FDA-b). (2021).  Coronavirus (COVID-19) Update: FDA Authorizes Additional Oral Antiviral for Treatment of COVID-19 in Certain Adults. Retrieved on Jan. 28, 2022 from https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-additional-oral-antiviral-treatment-covid-19-certain
  15. Vangeel, L., De Jonghe, S., Maes, P., Slechten, B., Raymenants, J., Andre, E., et al. (2021). Remdesivir, Molnupiravir and Nirmatrelvir remain active against SARS-CoV-2 Omicron and other variants of concern. bioRxiv. Retrieved from https://www.biorxiv.org/content/10.1101/2021.12.27.474275v1
  16. Wang, Y., Li, P., Solanki, K., Li, Y., Ma, Z., Peppelenbosch, M. P., et al. (2021). Viral polymerase binding and broad-spectrum antiviral activity of molnupiravir against human seasonal coronaviruses. Virology, 564, 33–38. doi:10.1016/j.virol.2021.09.009. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8486977/
  17. Willyard, C. (2021). How antiviral pill molnupiravir shot ahead in the COVID drug hunt. Nature. doi:10.1038/d41586-021-02783-1. Retrieved from https://www.nature.com/articles/d41586-021-02783-1
yael cooperman
Yael Cooperman, MD

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.

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