Merck to seek emergency authorization for oral Covid-19 treatment

Merck and Ridgeback Biotherapeutics plan to seek emergency authorization for their oral antiviral treatment for Covid-19, after the medicine showed “compelling results” in clinical trials.

The drug, molnupiravir, reduced the risk of hospitalization or death by around 50% for patients with mild or moderate cases of Covid-19, the companies announced on Friday. Molnupiravir is administered orally and works by inhibiting the replication of Covid-19 inside the body.

An interim analysis of a phase 3 study found that 7.3% of patients treated with molnupiravir were hospitalized within 29 days. Of the patients who received a placebo, 14.1% were hospitalized or died by day 29. No deaths were reported in patients who were given molnupiravir within the 29-day period, while 8 deaths were reported in placebo-treated patients.

All 775 trial participants had laboratory-confirmed symptomatic Covid-19 and were randomly allocated either molnupiravir or a placebo within five days of the start of their symptoms.

Every participant was unvaccinated and had at least one underlying factor that put them at greater risk of developing a more severe case of the virus. The most common risk factors included obesity, being over the age of 60, diabetes and heart disease.

The phase 3 part of the trial was conducted at more than 170 sites, in countries including the U.S., Brazil, Italy, Japan, South Africa, Taiwan and Guatemala.

Molnupiravir’s efficacy was not affected by the timing of symptom onset or patients’ underlying risk factors, the study showed. It also proved to be consistently effective in treating all variants of Covid-19, including the widely dominant and highly transmissible Delta strain.

Adverse events were comparable in both the molnupiravir and placebo groups, with around 10% reporting adverse events. Just 1.3% of the molnupiravir group discontinued therapy due to an adverse event – less than the 3.4% of the placebo group who did so.

Recruitment into the study is being stopped early due to the positive results, at the recommendation of an independent Data Monitoring Committee and in consultation with the U.S. Food and Drug Administration.

Merck is currently also trialing molnupiravir in a separate global phase 3 study to evaluate its efficacy in preventing the spread of Covid-19 within households.