Pfizer’s drug against Covid is called Paxlovid: the EMA has given emergency authorization to the drug. It may be available in January. It should work against all variants, including Omicron, but does not replace the vaccine
Has the so-called Pfizer pill been authorized?
Ema, the European Medicines Agency, has granted emergency authorization for Pfizer’s SARS-CoV-2 antiviral drug called
Paxlovid
for the treatment of adults with Covid who do not require oxygen and who are at increased risk of severe disease progression.
When will I arrive in Italy?
Probably since January, said Guido Rasi, consultant to the extraordinary commissioner for the Covid emergency, Figliuolo. The green light from Aifa, the Italian Medicines Agency, should arrive in days. What is the effectiveness of Paxlovid? Results from a study of 2,246 high-risk patients published by Pfizer show 89% effectiveness in preventing hospitalization and death.
When should it be taken and how should it be taken?
Paxlovid should be administered as soon as possible after the diagnosis of Covid-19 and in any case within 5 days of the onset of symptoms. Those who have Covid asymptomatic do not need it. The two active substances of the medicine, PF-07321332 and Ritonavir, available as separate tablets, must be taken together twice a day for 5 days. Can anyone take it? S. Apart from pregnant or breastfeeding women, who were excluded from the studies.
What is the mechanism of action of this drug?
a small synthetic molecule which, by blocking a component of the virus called protease, prevents the virus from having proteins matured at the right point to be able to reassemble and multiply. The drug does not prevent the virus from entering cells, but it blocks its replication.
What does it prevent?
It prevents pathology, that is the aggravation of symptoms and, consequently, protects against hospitalization.
Can it also be taken against contagion?
No. By blocking viral replication, however, Paxlovid eliminates the virus from the body making the subject who takes it free of the virus faster.
Does it replace the vaccine?
No: the vaccine is given to a healthy person to get the body ready to fight SARS-CoV-2 with its own immune system. Paxlovid (like other drugs) has a limited duration of action: the concentration of the active ingredients is lowered and, after a couple of days, the medicine will have disappeared from the body. The vaccine, on the other hand, acts on the immune system, which, after being trained, can fight the virus for months.
Can the drug be given to the vaccinated?
Could it complement vaccine immunity? Of course, if a vaccinated has the symptoms of Covid, albeit to a much lesser extent, he can run the risk of worsening (especially some categories of people who do not respond well to immunization), then the antiviral can be very useful.
What are the possible side effects?
The most common side effects reported in the study up to 34 days after the last dose of Paxlovid were dysgeusia (taste disturbances), diarrhea and vomiting. This drug is taken together with an antiviral used against HIV, Ritonavir, which increases the duration of action. As with many other drugs, some people may not tolerate the Paxlovid-Ritonavir combination.
Does this drug also work against variants? For example Omicron?
Pfizer said they have great confidence that Paxlovid will also remain effective against the Omicron variant based on in vitro data. For the type of drugs such as Paxlovid, the variants are absolutely irrelevant, because the mutations they present usually focus on the mechanisms by which SARS-CoV-2 attaches itself to the cell to penetrate inside, specifically, the spike protein. Variants can be a problem for monoclonals, which target the spike.
Can antivirals be used for that segment of the population that does not want to be vaccinated?
They are people who are more likely to get sick than others. The advantage for everyone, compared to monoclonals, that antivirals are pills to be taken by mouth and not through infusions. What is the sustainability of antivirals against SARS-CoV-2? Pfizer has stated that it will make available 80 million doses next year at different prices depending on the economic possibilities of the various countries. It is difficult to say how much it will cost the Italian health system, given that Aifa negotiates the cost of therapies with companies. They should cost less than monoclonals.
Could antivirals have a resistance problem in the future and therefore no longer be effective?
There may be two resistance mechanisms, one of the kinetic type, when the body increases the rate of elimination of the drug after some time, and we have no evidence that this can happen (it should concern chronic rather than acute therapies); then there is the resistance of the virus itself, but the drug target is currently a highly “conserved” molecule from the biological point of view, that is, such that, even when the virus changes, as written, it does not undergo any changes.
* Replied Gianni Sava, expert member of the Italian Society of Pharmacology (SIF) and coordinator of the SIF Magazine.
December 18, 2021 (change December 18, 2021 | 07:14)
© REPRODUCTION RESERVED
#Pfizers #antiviral #pill #arrive #Italy