covid 19 :Paxlovid what is the Pfizer anti Covid pill?

Home

 The Pfizer laboratory has designed an antiviral drug that would be able to reduce the risk of hospitalization and death after Covid infection by 89%. This is an orally administered pill called Paxlovid. What is its mode of action? Its side effects? Discovery.

covid 19 Paxlovid what is the Pfizer anti Covid pill


Pfizer has designed an oral treatment specifically designed to be administered orally at the first signs of Covid infection. This pill is called Paxlovid. On November 16, 2021, the U.S. pharmaceutical company applied for emergency use authorization from the U.S. Food and Drug Administration (FDA). How does this pill work? Its effectiveness against Covid? Its side effects? Knowledge to date.


What is Paxlovid?

The American pharmaceutical company Pfizer has developed an antiviral treatment, marketed under the name Paxlovid. If granted marketing authorizations, this pill, administered orally, could be taken at home in the first days after the onset of symptoms in case of Covid-19 infection. Paxlovid is a treatment similar to Molnupiravir, an antiviral drug developed by the American pharmaceutical company Merck. Already authorized since the beginning of November in the United Kingdom, this antiviral has been the subject of an application for emergency authorization in the United States, which must be examined on November 30 by the FDA. The French government would have ordered 50,000 doses, said Health Minister Olivier Véran at the end of October, pending validation by the European Medicines Agency.


How effective is it against Covid?

Paxlovid would be able to reduce the risk of hospitalization or death by 89%

In an interim phase 2/3 randomized, double-blind analysis conducted on more than 1,800 out-of-hospital patients in July 2021, all with at least one risk factor for developing a severe form of the disease, Pfizer showed that Paxlovid was able to reduce the risk of hospitalization or death by 89% compared to the placebo group,  reports the laboratory in a press release of November 5, 2021. Each patient received oral treatment or placebo every 12 hours for 5 days. 


For patients who received Paxlovid or placebo within 3 days of the onset of symptoms: 


  • Hospitalizations: 0.8% (3 of 389) of patients who received Paxlovid were hospitalized up to day 28 compared to 7% of patients (27 of 385) who received placebo.
  • Death: No deaths were reported in patients who received Paxlovid versus 7 in patients who received placebo.

For patients who received Paxlovid or placebo within 5 days of the onset of symptoms: 


  • Hospitalizations: 1% (6 of 607) of patients who received Paxlovid were hospitalized up to day 28 compared to 6.7% of patients (41 of 612) who received placebo.
  • Deaths: No deaths were reported in patients who received Paxlovid versus 10 in patients who received placebo.

"This data suggests that our oral antiviral candidate if approved or authorized by regulatory authorities, has the potential to save patients' lives, reduce the severity of COVID-19 infections and eliminate up to 9 out of 10 hospitalizations," said Albert Bourla, Pfizer's Chairman and Chief Executive Officer. Subject to approval or authorization, it could be prescribed more widely as a home treatment to help reduce the severity of the disease, hospitalizations, and deaths, as well as the likelihood of infection. After exposure, in adults.'


What is the composition of Paxlovid?

Paxlovid is composed of two molecules. The first PF-07321332 is the active agent that prevents the virus protein from replicating. The second is ritonavir, a protease inhibitor normally used for the treatment of HIV infections. "HIV is not related to coronaviruses and the replication of its genetic material is done through a different mechanism. But it also produces a poly-protein that must be cut 9 times by a protease to form the new viral particles," explains an article published in the scientific journal Médecine Science in June 2020.


Mode of action: how does Paxlovid work?

Paxlovid would prevent the coronavirus protease from replicating.

A protease is a virus-specific enzyme that acts on viral proteins to promote virus replication. To stop the replication of a virus, it is therefore necessary to reduce or prevent the protease from acting. Coronaviruses have two proteases, one of which is called SARS-CoV-2, 3CL. It is on this protease that paxlovid oral treatment acts. 


When will it be available?

The company says it has entered into advance purchase agreements with several countries and is in negotiations with several others.

At the moment, Paxlovid is not marketed. But faced with the "overwhelming efficacy" highlighted in its clinical trials, Pfizer decided to stop the trial earlier than planned and submitted an authorization dossier to the U.S. Food and Drug Administration (FDA) for an application for emergency use authorization (EUA) as soon as possible, the laboratory said in its statement of November 5, 2021. If the request is accepted, this pill could be administered in the United States and doses could be ordered by countries that wish to do so, such as France. The company says it has entered into advance purchase agreements with several countries and is in negotiations with several others. According to the Washington Post, the U.S. government plans to buy 10 million doses and invest up to $1 billion in the manufacture and distribution of Paxlovid. In addition, a voluntary licensing agreement, announced on 16 November, with the Medicines Patent Pool (MPP), has reportedly been voted. This patent sharing would allow generic manufacturers to produce the drug to supply to 95 middle- and lower-income countries.


What are the side effects?

Of the patients who participated in the study and received Paxlovid, 1.7% experienced serious adverse events and had to stop treatment. The active substance contained in this medicine, ritonavir, can cause side effects such as: 


  • diarrhoea,
  • nausea and vomiting
  • abdominal pain
  • throat irritation or cough
  • headache and dizziness
  • rash and itching

disturbances in sugar and fat metabolism with abnormal fat redistribution observed after several months of treatment (called lipodystrophy)

toxicity to the liver (increased transaminases) and pancreas. 

What is the price?

The price of the Paxlovid pill is not yet known. Nevertheless, Pfizer announced, in its statement, tiered pricing based on each country's income level to ensure equitable access for all and an affordable price. In other words, high- and upper-middle-income countries will pay more than low-income countries.


Sources

- PFIZER'S NOVEL COVID-19 ORAL ANTIVIRAL TREATMENT CANDIDATE REDUCED RISK OF HOSPITALIZATION OR DEATH BY 89% IN INTERIM ANALYSIS OF PHASE 2/3 EPIC-HR STUDY, November 5, 2021.


- Targeting the major protease of SARS-CoV-2 to manufacture an effective drug against this coronavirus, Medicine Science, June 2020.


google-playkhamsatmostaqltradent