QCOSTARICA – The United States Food and Drug Administration (FDA) this week authorized the emergency use of Paxlovid, the pill for the treatment of covid-19 for adults and for those over 12 years of age. What does this mean for Costa Rica? Is it a step forward to have access to this medicine?
According to the Ministry of Health, through its press office, reported that the situation is being monitored, without any decisions having yet been made on the entry of the drug into the country.
“The specialist teams in Pharmacoepidemiology of the CCSS (Caja Costarricense de Seguro Social) and the Ministry of Health remain vigilant in the face of new scientific evidence of therapies for covid-19, any decision that emanates from said analysis will be communicated proactively,” said the Ministry of Health.
In accordance with the procedure previously reported by Health, for a product with emergency use authorization (in U.S.) to be authorized in the country, the pharmaceutical company (in this case, Pfizer) must present the documentation of said temporary guarantee and its clinical studies to national authorities.
Based on the analysis of the regulator and the information from Pfizer, Health will decide if it also applies here and under what criteria.
In its statement, the FDA was emphatic that this treatment does not replace the vaccine, but would be used in people who become infected and due to very specific health conditions have not been able to receive the doses, or in specific situations in which the vaccine do not avoid the symptoms of the disease.
“The FDA urges the population to be vaccinated and to receive boosters if they are eligible (six months after completing the scheme),” the statement cites.
Paxlovid is only sold by prescription to those who have tested positive for SARS-CoV-2 (the virus that causes covid-19). To obtain the expected results, it should be ingested as soon as possible, ideally in the first five days after the onset of symptoms. It is aimed mainly at those who have risk factors for complications or death.
This product is based on two compounds called nirmatrelvir and ritonavir. The person takes two nirmatrelvir tablets and one ritonavir tablets twice a day for five days, for a total of 30 tablets. Treatment should not exceed five days.
“This authorization provides a new tool to combat covid-19 at a crucial moment in the pandemic in which new variants are emerging. This promises to make antiviral treatment more accessible to those most at risk of severity from covid-19,” said Patrizia Cavazzoni, director of the FDA’s Center for Research and Evaluation.
How does the pill work?
The purpose of this treatment is to prevent the virus from replicating, that is, creating copies of itself. This process allows it to become more numerous and attack more and better. Paxlovid inhibits a key protein in viral replication.
How do the two compounds work? Nirmatrelvir inhibits the production of a protein called protease that is essential in the generation of new copies of the virus.
“Protease is a very characteristic enzyme that coronaviruses have. In 2020, Pfizer scientists resume a work that began with another coronavirus, SARS, and looked for a way to inhibit this protein. They saw that this compound had a very high antiviral capacity and that it did not affect other proteins in human cells,” expressed in a previous interview Rafael Valdez, medical director of Anti-infectives at Pfizer.
Pharmacokinetic studies followed, looking at how the drug is distributed, processed, and eliminated in the body. There it was seen that the action of the molecule could be affected by the regular metabolism of the person. Then they used ritonavir, which stabilizes the concentrations of the antiviral, prevents the body from disposing of it prematurely and can act against the virus.
“Ritonavir does not have an antiviral effect, but it does have this effect of boosting the amounts, the concentrations, of antiviral in the body in sufficient amounts for it to work,” he added.
The FDA indicated that Paxlovid reduced the rate of covid-19 hospitalizations and death by 88% when compared to a placebo. Furthermore, after 28 days, 6% of the 1,046 people in the placebo group died, versus none of the 1,039 in the group taking Paxlovid.
The most common side effects include altered sense of taste, diarrhea, muscle pain, and rises in blood pressure. It cannot be given to people with uncontrolled HIV infection or to those with liver problems.
Pharmaceutical MSD also has an antiviral pill that prevents viral replication, but uses a different route to achieve it. This other drug causes the virus to make mistakes when replicating itself, thereby weakening its copy-making process.
Initially, the efficacy of this drug had been reported as 50%, but later trials determined that it was 30%. This product already has the emergency endorsement of the European Medicines Agency (EMA, for its acronym in English).
It’s emergency authorization, not approval
An emergency authorization is not an approval. According to the FDA website, an Emergency Use Authorization (EUA) is a temporary endorsement.
It occurs when a product that has not yet been approved (but is in its final stages of study) shows that it could be helpful in diagnosing, treating, or preventing serious, life-threatening diseases or conditions for which there is still no diagnosis. , treatment or prevention.
It can also be used if there is an approved product with these characteristics, but it is scarce and not available.
In this case, there are no alternatives to what Paxlovid does to attack mild to moderate symptoms in those with risk factors.