Paxlovid is approved to treat patients with mild-to-moderate COVID-19 infection who are at risk of developing more severe disease

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The Medicines and Healthcare products Regulatory Agency (MHRA) has given the go-ahead for the antiviral medicine Paxlovid to be used to treat those patients with mild-to-moderate COVID-19 infection who are at risk of developing more severe disease. The drug, developed by Pfizer, is an antiviral treatment with a combination of two active ingredients—ritonavir and PF-07321332—and comes as separate tablets that are taken together orally twice a day for 5 days.

This is now the third antiviral COVID-19 pill approved for use in the UK. In November 2021, the MHRA gave authorisation for molnupiravir (Lagevrio) from Ridgeback Biotherapeutics and Merck Sharp & Dohme; then, in early December 2021, the MHRA approved the use of sotrovimab (GlaxoSmithKline and Vir Biotechnology) for patients with mild-to-moderate COVID-19 who are at risk of developing severe disease.

The antiviral drugs prevent the virus from multiplying by inhibiting a protease enzyme required for virus replication. Ritonavir is a well-established drug used alongside some HIV drugs to boost their activity. In this new combination, it plays a similar role—by slowing down the breakdown of PF-07321332, ritonavir helps to increase the effectiveness of PF-07321332.

Clinical trial data suggest that a 5-day course of treatment with Paxlovid reduced the risk of COVID-19-related hospitalisation and death within 28 days for high-risk adults by 89% compared with those in the placebo group, when treatment was started within 3 days of COVID-19 symptom onset. Specifically, there were 3 (0.8%) hospitalisations and deaths in the group of 389 patients who received Paxlovid, compared with 27 (7%) hospitalisations and deaths in the placebo group of 385 patients.

Another oral COVID-19 treatment

The MHRA said that the approval of Paxlovid ‘follows a rigorous review of its safety, quality, and effectiveness’, including expert advice from the Government’s independent scientific advisory body, the Commission on Human Medicines.

Professor Sir Munir Pirmohamed, Chair of the Commission on Human Medicines, said: ‘The Commission on Human Medicines and its COVID-19 Therapeutics Expert Working Group has independently reviewed the data and endorses the MHRA’s regulatory approval of Paxlovid.’

Dr June Raine, MHRA Chief Executive, added: ‘We now have a further antiviral medicine for the treatment of COVID-19 that can be taken by mouth rather than administered intravenously. This means it can be administered outside a hospital setting, before COVID-19 has progressed to a severe stage.’

The clinical trial data suggest that Paxlovid is most effective when taken during the early stages of infection, so the MHRA recommends its use as soon as possible and within 5 days of the start of symptoms. It has been authorised for use in people aged 18 years and above who have mild-to-moderate COVID-19 infection and at least one risk factor for developing severe illness—these include obesity, older age (>60 years), diabetes mellitus, or heart disease.

The MHRA commented that ‘similar favourable results were seen in patients when treatment was started within 5 days of the start of symptoms’.

One of the first in the world to approve Paxlovid

The Health and Social Care Secretary, Sajid Javid, congratulated the MHRA, saying: ‘The UK has been a world leader at finding and rolling out COVID-19 treatments to patients. This is further proved by the MHRA being one of the first in the world to approve this life-saving antiviral.’

The MHRA explained that it is too early to know whether the Omicron variant has any impact on Paxlovid’s effectiveness, but they are proactively working with the company to establish this.

Professor Pirmohamed added: ‘As [Paxlovid] is deployed, we will monitor its effectiveness and safety in the real world, including any drug interactions, as we do with all medicines. Any side effects should be reported to the MHRA using the Yellow Card scheme.’

This article originally appeared on Medscape, part of the Medscape Professional Network. 

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