Paxlovid: the corona drug - properties, studies, side effects
Created: 01/12/2022, 1:55 PM
From: Dominik Jahn
Paxlovid: the corona drug - properties, studies, side effects.
© dpa / Frank Hoermann / SVEN SIMON
Paxlovid: In the fight against Corona, research after vaccines is increasingly turning to drugs.
Vaccines are currently the big plus in the fight against corona.
In addition to the mRNA vaccines from Biontech, Moderna and the vector vaccine AstraZeneca, the protein-based vaccines such as Novavax and the dead vaccine from Valneva are the bearers of hope.
Most recently,
echo24.de
* also reported on the Sanofi vaccine.
But research also looks at the alternative of drugs.
With Paxlovid it could be that time soon.
In the past few months, the manufacturer Pfizer has intensified its efforts to find an effective drug against the coronavirus.
In cooperation with Biontech, the company has already celebrated great successes in the manufacture of vaccines.
The developed mRNA vaccine is already being used successfully.
Paxlovid: the properties of the new drug from Pfizer
With Paxlovid, the company now wants to take another step.
As the
Pharmazeutische Zeitung
writes, the drug is
“a combination therapy of two oral antiviral agents
”.
One substance is therefore
“the new substance PF-07321332 developed by Pfizer, which is now called Nirmatrelvir and which inhibits the viral protease 3CL, which is important for the multiplication of SARS-CoV-2, and the well-known ritonavir, which is used as a booster works by slowing the breakdown of nirmatrelvir by CYP3A4 in the liver ”
.
3CL protease
By definition, the 3CL protease is the main protease of the coronavirus.
The 3CL protease corresponds to the non-structural protein 5 (nsp5) of the coronavirus and is responsible for the replication of the virus.
According to initial findings, paxlovid must be administered with a dose of 300 milligrams of nirmatrelvir and 100 milligrams of ritonavir.
The whole thing twice a day for a period of five days.
Phase I study of paxlovid
As early as the end of March 2021, Pfizer reported that the drug was entering an initial study phase. At that time Paxlovid still had the designation PF-07304814. As the
Pharmazeutische Zeitung
writes in a report, Professor Dr. Ralf Bartenschlager, President of the German Society for Virology, explained at an online press conference of the Science Media Center that it was about “another protease inhibitor against SARS-CoV-2 in clinical development, but this must be administered intravenously. This application route is actually only an option for Covid-19 patients who have already been admitted to the hospital ”.
In the phase I study, paxlovid was then tested in different doses in adults in the USA.
It was about the safety and tolerability of the drug.
Even at this early point in time, experts assumed, according to the article, that it would also
“work against other coronaviruses, which gives hope for a broad-spectrum antiviral also against new virus types from the corona family”
.
Phase II / III study of paxlovid
Further positive reports from the phase II / III study for paxlovid followed in November 2021.
Pfizer published important results in a press release.
As the company writes, Paxlovid was shown to "
reduce the risk of hospitalization or death by 89% compared to placebo in non-hospitalized high-risk adults with COVID-19."
However, the patients had to be treated within three days of the first symptoms of corona disease.
A total of 2,246 participants took part in the study.
The phase II / III study of Paxlovid started in July 2021. Within the observation period of 28 days, according to the study, of 697 patients treated with Paxlovid, only five were hospitalized - none of them died.
In contrast, 44 in the placebo group of 682 patients had to go to hospital.
Ten of them died in the course of treatment.
As the Pharmazeutische Zeitung writes about the study, the data also show that the viral load has changed.
It says:
“This was recorded in 499 patients.
Paxlovid reduced the viral load within five days by a factor of about 10 (0.93 log10 copies / ml) compared to placebo ”
.
According to Pfizer, this is the strongest viral load-reducing effect reported to date for an oral Covid-19 drug.
Side effect of paxlovid, according to the study
The studies also focused on the possible side effects of paxlovid. In the official Pfizer announcement after the Phase II / III study, there was no significant difference in side effects between participants who received the drug and those who were in the placebo group. All symptoms were "
mild in intensity"
.
It also said about the side effects:
“Among the patients who were evaluable with regard to treatment-related side effects, less serious side effects (1.7% vs. 6.6%) and the discontinuation of the study drug were due to patients who were treated with Paxlovid of adverse events (2.1% vs. 4.1%) observed compared to placebo. “
*
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