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Scientific Corner

What We Know About the New COVID-19 Antiviral Pills
Dr. Hatem Abushammala, Assistant Professor, Environmental and Public Health Department

Four months ago, the U.S. Food and Drug Administration (FDA) authorized the first oral antiviral drug to
treat COVID-19. Pfizer developed the treatment in pill form under the name Paxlovid, which consists of
co-packaged nirmatrelvir and ritonavir tablets. The nirmatrelvir tablets can stop COVID-19 replication by
inhibiting its protein, while the ritonavir tablets can keep the nirmatrelvir concentrations in the body in
the therapeutic range by hindering its degradation. Experts believe that Paxlovid is effective against the
latest COVID-19 variants, Delta and Omicron, because it attacks the virus life cycle stopping its replication
rather than merely triggering our bodies to generate antibodies. The treatment involves taking two
nirmatrelvir tablets and one ritonavir tablet together twice daily for five days.

Paxlovid is mostly used to treat mild to moderate COVID-19 cases in adults and children 12 years and
older. It is not a substitute for vaccination, is not designed to prevent COVID-19, for cases requiring
hospitalization due to severe COVID-19, or for those who are asymptomatic. In addition, it should be
used with caution in patients with pre-existing liver and kidney diseases, liver enzyme abnormalities,
or liver inflammation. Some possible side effects of this medication include an impaired sense of taste,
diarrhea, high blood pressure, and muscle aches.

A second drug, Molnupiravir, developed by Merck, was authorized by the FDA a day after the authorization
of Paxlovid. It is taken as four tablets twice a day. Both drugs have effectively reduced hospitalization
and death due to COVID-19 if taken within days of the onset of symptoms. However, trials showed that
Paxlovid is significantly more effective than Molnupiravir, reducing the risk of hospitalization and death
in high-risk unvaccinated people by 88% compared to 30% with Molnupiravir.

The side effects of Molnupiravir are like those of Paxlovid, but it is not authorized for anyone under 18
years old because it may negatively impact bone and cartilage growth and should not be administered
to pregnant women because it can lead to birth defects. In addition to these two drugs, the FDA cleared
an intravenous antiviral medication called Veklury from Gilead Sciences, mostly administered at clinics.

References:
• Food and Drug Administration (FDA) (2021). Coronavirus (COVID-19) Update: FDA Authorizes First Oral Antiviral for Treatment
of COVID-19. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-first-oral-
antiviral-treatment-covid-19
• Knvul Sheikh, The New York Times (2022), New Antiviral Pills Help Treat Covid. Here’s How to Get Them. https://www.nytimes.
com/explain/2022/03/21/well/covid-antiviral-pills
• Dennis Thompson, WebMD (2021). The New COVID Antiviral Pills: What You Need to Know. https://www.webmd.com/lung/
news/20211229/the-new-covid-antiviral-pills-what-you-need-to-know#1

Abu Dhabi University | The College of Health Sciences E-Magazine | Issue 2 2021-2022 Academic Year