Pfizer’s anti-covid pill, presumably arriving in early 2022, will need to be administered as soon as possible after diagnosis and within 5 days of onset of symptoms. The therapy lasts 5 days and is not recommended during pregnancy, while breastfeeding women will have to stop feeding their babies during treatment. These are the indications of the European Medicines Agency Ema on the use of Paxlovid (PF-07321332 and ritonavir). The Agency’s advice can now be used to support national recommendations on the possible use of the medicine before marketing authorization.
This drug, while not yet authorized in the Union, can be used to treat adults with Covid who do not require supplemental oxygen and who are at increased risk of progression to a serious disease.
The Ema indication on the use of the Pfizer pill is based on the interim results of the main study conducted on non-hospitalized and unvaccinated patients who had a symptomatic disease and at least one underlying condition that put them at risk of severe Covid.
These data – the agency details – showed that Paxlovid reduced the risk of hospitalization and death when treatment was started within 5 days of the onset of symptoms. About 1% of patients (6 out of 607) who took the drug were hospitalized within 28 days of starting treatment compared with 6.7% of patients (41 out of 612) who were given placebo ( fictitious treatment); none of the patients in the treated group died, compared with 10 patients in the placebo group. In terms of safety, the most common side effects reported during treatment and up to 34 days after the last dose were dysgeusia (taste disturbances), diarrhea and vomiting.
The two active ingredients of the medicine, PF-07321332 and ritonavir, available in separate tablets, must be taken together 2 times a day for 5 days, explains the EMA which has prepared the ‘guide’ to support those national authorities who decide on a use of the medicine before its marketing authorization, for example in emergency settings, in light of the increase in infection rates and deaths due to Covid across the EU.
Paxlovid should not be used with some other medicines – Ema then specifies – both because due to its action it can lead to harmful increases in their blood levels, and because on the contrary some drugs can reduce the activity of Paxlovid itself. The list is included in the proposed terms of use.
The anti-Covid pill should also not be used in patients with severely reduced kidney or liver function. Paxlovid is not recommended during pregnancy, but also in women who are not using contraceptives and can become pregnant. These recommendations are due to the fact that laboratory studies in animals suggest that high doses of the drug may have an impact on the growth of the fetus. The proposed conditions of use will be published shortly on the Ema website.