First Antiviral COVID-19 Pill Paxlovid Approved in the United States
Anika H. Ahmed, MD
On Wednesday, December 22, 2021, the highly anticipated news was received with a sigh of relief by people across the globe that the United States Food & Drug Administration has given an emergency authorization for the first COVID-19 antiviral pill, Paxlovid, manufactured by the pharmaceutical company Pfizer.
Although it is not a cure for Omicron or other variants of Coronavirus, including Delta, it does promise a marked reduction in risk, of both hospitalization and deaths, by 89%, if given to COVID-19 patients within three days of the appearance of symptoms. Moreover, if given within five days of symptom appearance, the pill still has the efficacy of reducing the risk of severe symptoms development, by 88%.
This much-needed antiviral pill named Paxlovid is actually a combination of the existing antiviral drug Ritonavir (previously used to treat Human Immunodeficiency Virus, causing AIDS) and the newly developed drug Nirmatrelvir. These two combined drugs work together as a protease inhibitor to disrupt the multiplication of Coronavirus in COVID-19 patients.
It must be noted that this pill does not stop the transmission of COVID-19 and is not a replacement for available vaccination, which still remains the first line of defense against COVID-19.
The Paxlovid dosage protocol is to take two tablets of Nirmatrelvir and one tablet of ritonavir, twice per day for five days. It promises to reduce the more severe symptoms of COVID-19 and will now be a new tool in the pandemic fight, along with the approved COVID-19 vaccines. It is designed to block the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate. In the successfully conducted clinical trials with positive Coronavirus, patients took a combination of ritonavir, a drug used to treat HIV, with Nirmatrelvir and it reduced the risk of hospitalization or death by 89% when taken within three days of symptoms. According to Pfizer, the ritonavir drug allows the medication to remain active in the body longer, at higher concentrations.
More good news came from President Joe Biden after approval of Pfizer’s Paxlovid by FDA, who announced that Paxlovid will be easily available and shall be free of cost, and that his administration has already purchased 10 million courses. As approved, the two 150 mg tablets would be administered upon the first appearance of symptoms or a positive COVID-19 test result and continued over a five-day treatment course.
Compared to Paxlovid, Merck developed an antiviral pill with Ridgeback in mid-October this year and after receiving emergency authorization in November, it was given to patients in the United Kingdom as a national ongoing study and it can reduce the risk of hospitalization and death by 30%, if taken within five days of the onset of symptoms for people who have tested positive and are at higher risk of serious illness and hospitalization.
Also, it is anticipated that there is a reduced chance of drug resistance developing, as Paxlovid will be administered only for a short course of five days and the Coronavirus will not develop drug resistance as some antibiotics have shown to develop in the past due to longer time multiple dosage.
Very informative!