Merck (MSD) and Ridgeback Biotherapeutics have reported that their experimental oral Covid-19 antiviral therapy, molnupiravir (MK-4482, EIDD-2801), decreases hospitalisation or mortality risk in the Phase II/III MOVe-OUT clinical trial.

An oral form of a potent ribonucleoside analogue, molnupiravir hinders the SARS-CoV-2 viral replication.

Invented by biotech firm Drug Innovations at Emory (DRIVE), the therapy was licensed by Ridgeback and is currently being developed with Merck.

The placebo-controlled, double-blind, randomised and multicenter trial is assessing the efficacy, safety and pharmacokinetics of molnupiravir in mild or moderate Covid-19 patients aged 18 years and above, who are not admitted to the hospital.

Furthermore, subjects with the development of symptoms within seven days before randomisation will be part of the trial.

According to data available from 1433 subjects, hospitalisation or mortality risk was 9.7% in the placebo arm versus 6.8% in subjects who received molnupiravir, indicating an absolute and relative risk reduction of 3% and 30%, respectively.

Furthermore, nine cases of death were observed in the placebo arm while only one case was reported in the molnupiravir arm.

Molnupiravir’s adverse event profile was in line with the profile noted at the planned interim assessment of the trial.

On meeting the statistical criterion for success, subject recruitment was stopped at the advice of the external Data Monitoring Committee, which was approved by the US Food and Drug Administration (FDA).

As reported earlier, molnupiravir substantially reduced the risk of hospitalisation or mortality from 14.1% in the placebo arm versus 7.3% in the molnupiravir arm, signifying a 48% relative decline in risk.

Merck noted that the interim data, as well as the data from further assessments, support the oral medicine’s effectiveness and overall favourable benefit-risk assessment to treat mild to moderate Covid-19 in adults who are at increased risk for disease progression.

The oral pill is currently authorised for use by the Medicines and Healthcare products Regulatory Agency in the UK.

Last month, Merck sought emergency use authorization from the US Food and Drug Administration for the antiviral to treat Covid-19.