The United Kingdom is the first country in the world to approve Lagevrio (molnupiravir), an oral antiviral drug for the treatment of COVID-19 infection caused by the new coronavirus SARS-CoV-2 and presenting with mild-to-moderate severity. Lagevrio is approved for use in adult patients with at least one risk factor for developing severe illness.

The decision was made by the United Kingdom Medicines and Healthcare products Regulatory Agency (MHRA). The verdict is conditional, meaning that Lagevrio, which was developed by Merck & Co. and Ridgeback Biotherapeutics, has yet to prove its own efficacy for full approval.

The antiviral drug molnupiravir works according to the mechanism of the so-called viral error catastrophe: it integrates into SARS-CoV-2 RNA, which leads to accumulation of errors in the viral genome, and this is followed by suppression of viral replication.

The recommended dose of Lagevrio is 800 mg (four 200 mg capsules) taken orally every 12 hours for 5 days. Lagevrio should be given as soon as possible after the diagnosis of COVID-19 and no later than 5 days after symptoms appear.

Merck & Co. has entered into supply and advance purchase agreements for molnupiravir with the U.K. Government for 480,000 courses of therapy.

The application of molnupiravir is under review by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA).


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The positive MHRA decision is based on interim results from the MOVe-OUT (NCT04575597) phase 3 (randomized, double-blind, placebo-controlled, multicenter, international) clinical trial, which enrolled non-hospitalized adult patients (n=775) with a laboratory-confirmed diagnosis of COVID-19 coronavirus infection with mild to moderate severity.

Among the mandatory criteria for inclusion in the trial: absence of COVID-19 vaccination; at least one risk factor for poor outcomes (age 60 years or older, diabetes mellitus, obesity, chronic kidney disease, serious cardiovascular disease, chronic obstructive pulmonary disease, cancer in active stage); period of manifestation of disease symptoms not longer than 5 days before randomization.

Main characteristics of participants: median age 44 years (18–88); 14% aged 60 years or older and 3% older than 75 years; 49% received molnupiravir or placebo within 3 days of manifestation of COVID-19 symptoms; major risk factors: obesity in 77% of subjects, age 60 years or older in 14%, and diabetes mellitus in 14%.

Patients were given placebo or 800 mg of Lagevrio — orally every 12 hours for 5 days.

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The primary endpoint was the proportion of patients hospitalized and/or died from the time of randomization to day 29 of the study.

According to an interim analysis of the data collected, there were 7.3% of patients (n=28/385) in the molnupiravir group versus 14.1% in the placebo group (n=53/377) who experienced these outcomes. Administration of molnupiravir provided an absolute 6.8% reduction in risk of hospitalization or death (95% CI: −11.3 — −2.4), equivalent to a risk reduction relative to placebo of approximately 50% (p=0.0012).

There were no fatalities among those receiving Lagevrio, compared to 8 in the control group.

The therapeutic efficacy of molnupiravir was independent of the duration of COVID-19 symptoms or the specificity of the risk factor, including patient age. Molnupiravir demonstrated consistent efficacy against viral variants, including the Gamma, Delta, and Mu strains of SARS-CoV-2, which accounted for nearly 80% of MOVe-OUT infections.

The safety profile of molnupiravir was generally not different from that of placebo: 35% and 40% of subjects experienced adverse reactions, with adverse events caused by administration of the drug in 12% versus 11% in the control group.

Among the most common adverse events in the Lagevrio group were: diarrhea (in 3% of patients), nausea (2%), dizziness (1%), and headache (1%). All adverse reactions were mild to moderate in severity.



Lagevrio (molnupiravir): summary of product characteristics. [PDF]

Lagevrio (molnupiravir): patient information leaflet. [PDF]

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