Among the Covid treatment opportunities, antivirals are assuming great importance. Here is a guide to the key medicine in the fight against the virus also because it allows to avoid hospitalization that weighs both on the accounts of the National Health Service and on the psychological stability of the infected, especially the elderly and / or frail. An important drug but the effect of which the virus can often return.
Antiviral drugs: what are they?
The antivirals for Covid-19 approved by AIFA are the Veklury (Gilead trade name of the active ingredient remdesivir), il Lagevrio (Merck trade name of the active ingredient molnupiravir) and the Paxlovid (Pfizer brand name for the drug consisting of the active ingredients nirmatrelvir and ritonavir). They are indicated to stop the replication of the virus in patients at risk of severe forms of the disease, avoiding hospitalization.
Paxlovid: it is a combination of Nirmatrelvir (specific antiviral against Sars-CoV-2) and ritonavir, an old antiviral used against HIV. It is administered orally, through two different tablets that contain the two active ingredients. Ema has recommended its use for the treatment of Covid-19 in adults who do not need supplemental oxygen therapy – and therefore still have a mild to moderate form of Covid – and who are at increased risk of progressing to severe disease. . For these patients, if administered within 5 days of positivity, Paxlovid can reduce hospitalizations and deaths due to Covid-19 by 89%: this is shown by analyzes published in the New England Journal of Medicine.
Veklury: is an antiviral that the EMA recommends for adults and adolescents 12 years of age and older with pneumonia that requires supplemental oxygen. And for adults who, while not requiring supplemental oxygen, are exposed to a greater risk of developing a severe form of Covid-19. It is given by infusion into a vein (200 mg on the first day, and then 100 mg once a day).
The overall duration of treatment should be between 5 and 10 days for adults and adolescents with pneumonia and a need for supplemental oxygen. On the other hand, for adults at risk who do not need supplemental oxygen, the treatment lasts three days and should be started as soon as possible after the diagnosis of Covid-19 and within 7 days of the onset of symptoms.
Lagevrio: is an oral antiviral. Its use, according to the AIFA authorization, is indicated within 5 days of the onset of symptoms for the treatment of non-hospitalized Covid-19 patients, with mild-moderate disease and at risk of contracting the severe form of the disease. Risk factors for prescribing molnupiravir include chronic renal failure (excluding patients on dialysis), solid or blood cancers being treated, primary or acquired immunodeficiency, obesity, severe cardiovascular disease, uncompensated diabetes mellitus. Treatment involves taking 4 tablets of 200 mg twice a day for five days. To date, the drug is not recommended for children under 18 and for pregnant or breastfeeding women.
In studies evaluated by the EMA, Lagevrio reduced the risk of hospitalization of people positive for Covid-19 and most at risk of developing the severe form of the disease to 6.8%.
How do they work?
Paxlovid: nirmatrelvir is a protease inhibitor: once it enters cells, it inhibits the activity of an enzyme (the viral protease 3CL) used by the virus to assemble its proteins. Thus the virus can no longer replicate. Ritonavir serves to increase the duration of action of nirmatrelvir by slowing its breakdown. As the stage in which the virus replicates the most is the initial stage of the infection, i.e. the first five days, it is important that the antiviral is administered while the patient is still in this stage. After that, effectiveness is lost, because at that point the greatest damage to the patient is done by the immune response to the virus that has already replicated sufficiently.
Veklury: the active ingredient, remdesivir, stops the virus from replicating in cells by inhibiting the viral enzyme Rna polymerase, used by the virus to copy its genetic material and form new virions.
Lagevrio: the number of mutations in the RNA of the virus increases, according to a mechanism called “catastrophe of viral errors”: the accumulation of errors in the virus genome, induced by the drug, makes the virus unable to replicate. A new study published on Annals of Internal Medicine – among the authors also the infectious disease specialist Matteo Bassetti – shows that the drug reduces the need for respiratory interventions and emergency visits for patients at risk.
Who can prescribe them?
According to AIFA directives, “the selection of the patient is entrusted to general practitioners, to those of the Usca, who can refer patients suffering from recent Covid onset to the structure where to carry out the prescription” (ie the Covid-19 specialist centers identified from the Regions).
From 21 April, the Paxlovid It can also be prescribed by general practitioners, and is available – on a doctor’s prescription and at no cost to the citizen – in pharmacies throughout the country (before that date, family doctors could only indicate the patient, so that he was treated in hospitals and designated facilities, and the drug was not distributed in pharmacies). To date, antivirals appear to be underused in our country: as explained a Republic by the infectious disease specialist Andrea Gori, of the 600,000 packs of anti Covid pills purchased in January 2022, only just over 52,000 have been used in these six months.
Side effects?
Paxlovid: Adverse events recorded during clinical trials are: impaired taste (6%), diarrhea (3%) and hypertension (1%).
Veklury: The most common side effect (present in about 10% of cases) is nausea, combined with an increase in the levels of liver enzymes in the blood, a sign of liver problems.
Lagevrio: the most common side effects: nausea, diarrhea, dizziness (about 10% of cases).
(sources: Ema, Aifa, Veronesi Foundation)