Friday, December 8

How Paxlovid, Pfizer’s Antiviral Works

When on December 22 United States Drug Agency (FDA gave the Emergency Use Authorization to Paxlovid, the treatment antiviral against the Covid-19 developed by Pfizer of which the Spanish president Pedro Sanchez announced this Monday the purchase of 340,000 doses, one of the heads of the federal agency, Patrizia Cavazzoni, defined it as “a big step forward in the fight against the global pandemic ”of coronavirus. The president of the United States, Joe Biden, before the great advantage of a treatment that was the first oral in the fight against the pandemic, an advantage over monoclonal antibody treatments that require transfusions or injections, called it a ‘game changer’ with the potential to “dramatically alter the course of the pandemic.”

Paxlovid is composed of of medicines. One is nirmaltrelvir, a drug that works on cells inhibiting an enzyme that the virus produces to replicate, the Mpro. The other is ritonavir, a protease inhibitor used to fight Against AIDS and that, in this case, it helps nirmaltrelvir stay active longer in the body.

The treatment, which has been given the green light for moderate cases of covid -19, is authorized for use in high-risk adults and to minors from 12 years old as long as these weigh more than 40 kilos. It should be prescribed by a doctor after infection is confirmed and start taking it within the first five days with symptoms. In his clinical trial he demonstrated a 88% reduction in hospitalizations and deaths.

In the treatment, three tablets (two of nirmaltrelvir and one of ritonavir) are taken at the same time twice a day for five days, for a total of 30 tablets in five days. Its potential side effects include diarrhea, muscle aches, increased blood pressure, and loss of taste.

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Paxlovid is not recommended for people with severe kidney or liver problems. It also should not be taken with certain medications, including statins commonly used to lower cholesterol, because ritonavir can interfere with them. Doctors may also recommend stopping the intake of other medications for a few days or adjusting the dose given that they warn of “potential significant interactions ”with other drugs. The FDA published a list of drugs whose consumption along with Paxlovid is contraindicated.

Pzifer treatment has not been tested in pregnant women and the package insert recommends discussing the possible benefits and risks of its use with your doctor. It may also interfere with the contraceptive pill and it is recommended to use different methods of contraception while taking Paxlovid.

Although shortly after the authorization of the treatment from Pfizer came another similar from Merck, Molnupavir, the effectiveness of the latter is much lower and is estimated at 30%.

Scarcity in the US

The reality that the United States has encountered so far is that of shortage of Paxlovid, a treatment that was developed by Pfizer in less than two years and in which the tablets were manufactured before the summer but which has a production process that causes them to take time six to eight months to produce the pills. New York, for example, received 1,300 treatments in late December but sold out within a week.

The federal government initially announced the purchase of 10 million treatments, at a price of $ 530 per unit (slightly less than 470 euros), already at the beginning of this year doubled the order a Pfizer. Washington distributes the treatment to the statesFor now depending on the size of the population, although a system similar to that used for monoclonal antibody treatments is being considered and distributed according to infections and hospitalizations. Then it’s the local authorities who decide where to send them. The focus is on people with weaker immune systems but lack of supply is forcing many physicians to give priority to unvaccinated people versus others at high risk who are already immunized.

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The pharmaceutical company, in a call with analysts, assured that this year expects to reach 155 million people in rich countries already 95 million people in nations of low income in 2022.

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