The new promising oral antiviral therapy has shown a lower risk of hospitalisation and low mortality when compared to placebo. Pfizer Pharmaceuticals believes the findings of a trial on Paxlovid are a 'game changer' in the battle against COVID-19.

What is PAXLOVID?

PAXLOVID is an investigational SARS-CoV-2 protease inhibitor antiviral therapy that has been designed specifically for oral administration, allowing it to be prescribed at the first sign of infection or awareness of exposure, potentially helping patients avoid severe illness that can result in hospitalisation and death.

PAXLOVID^TM (PF-07321332) is an inhibitor of the SARS-CoV-2-3CL protease, an enzyme required for the coronavirus to reproduce. Co-administration of PF-07321332 with a modest dosage of ritonavir slows the metabolism, or breakdown, of the drug, allowing it to stay active in the body for extended periods of time at greater concentrations to help treat the virus.

PF-07321332 suppresses viral replication at the proteolysis step, which occurs prior to viral RNA replication. PF-07321332 did not exhibit signs of mutagenic DNA interactions in preclinical tests.

EPIC-SR is a cohort of immunised individuals who have an acute COVID-19 infection and are at risk for severe disease. Pfizer began the Phase 2/3 EPIC-PEP (Evaluation of Protease Inhibition for COVID-19 in Post-Exposure Prophylaxis) trial in September to assess the effectiveness and safety of the drug in adults exposed to SARS-CoV-2 via a household member.

Strike early and strike hard

The company said that the drug's statistics are based on mid-to-late stage research of 1,219 people who had at least one underlying medical condition and a laboratory-confirmed infection during a five-day period. Additionally, participants received a modest dosage of ritonavir, a medicine routinely used in combination HIV therapies.

Pfizer will discontinue further enrollment in the study on the recommendation of an independent Data Monitoring Committee and in consultation with the US Food and Drug Administration (FDA) due to the overwhelming efficacy demonstrated in these results and plans to submit the data as part of its ongoing rolling submission to the US FDA for Emergency Use Authorisation (EUA) as soon as possible.

Why it is important?

An important pandemic-fighting strategy is antiviral medications since not everyone will be inoculated against the virus and it may take years to properly inoculate individuals in some countries, especially given the existing gaps in global vaccine supplies to do so.

According to Pfizer CEO, Albert Bourla:

"These statistics indicate that, if authorised by regulatory authorities, our oral antiviral candidate has the potential to save patients' lives, significantly decrease the severity of COVID-19 infections, and avoid up to nine out of ten hospitalisations." 

Unlike Gilead Sciences' intravenous medication remdesivir, the treatments from Pfizer and Merck may be taken orally. While immunisations remain the greatest source of protection against the virus, health officials believe that tablets like these may help prevent the illness from advancing in individuals who are sick and avoid hospitalisation.

Merck and Ridgeback Biotherapeutics announced on October 1st that they have created a medication that, when used alone, significantly decreases the risk of hospitalisation or mortality in patients with mild or moderate COVID. Merck's antiviral tablet has been authorised by the British drugs authority.

Preparing for the next move 

1. Additional antivirals are being developed. Gilead Sciences is in the process of creating a tablet form of remdesivir. If the antiviral were administered at the same time that molnupiravir is when symptoms have just begun to manifest and virus levels are high, it would be equally successful.
2. Researchers presented findings from a study presented at IDWeek, a virtual gathering of infectious-disease experts and epidemiologists held earlier this month. The trial included daily infusions of remdesivir to persons with COVID-19 in the early stages. Although the trial included a limited number of subjects, remdesivir seemed to minimise hospitalisations by 87 per cent in persons at high risk of developing COVID-19.
3. Atea Pharmaceuticals, based in Boston, Massachusetts, is also developing an antiviral. When SARS-CoV-2 developed, it was evaluating a nucleoside analogue against hepatitis C in a clinical investigation.
4. After the pandemic halted the experiment, Atea shifted its attention to COVID-19. Now, it has formed a partnership with Roche in Basel, Switzerland, to further the development of its chemical.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author is a practising super specialist from New Delhi.