Merck/RidgebackBioMerck (NYSE: MRK) and its partner Ridgeback Biotherapeutics have won emergency use authorization from FDA for the investigational oral antiviral molnupiravir (MK-4482, EIDD-2801). 

In late November, an FDA advisory panel narrowly voted in favor of authorizing molnupiravir

FDA recently also granted emergency use authorization to Pfizer’s (NYSE:PFE) oral SARS-CoV-2 antiviral Paxlovid (nirmatrelvir and ritonavir). 

FDA’s authorization of molnupiravir covers its use to treat mild-to-moderate COVID-19 in individuals at least 18 “who are at high-risk for progression to severe COVID-19.” The authorization constrains the use of the drug to individuals who cannot feasibly use other authorized COVID-19 treatments. FDA does not recommend the medication for patients who are hospitalized with COVID-19. 

The authorization does not support the use of molnupiravir as pre-exposure or post-exposure prophylaxis for COVID-19.

Molnupiravir

Molnupiravir image courtesy of Merck.

FDA recommends that patients taking the drug do so as soon as possible after receiving a positive COVID-19 diagnosis and within five days after symptoms arise. 

One course of treatment includes four 200 mg capsules of the drug every 12 hours for five days. 

Molnupiravr is a nucleoside analog that causes viral mutagenesis. 

The FDA recommended that pregnant individuals avoid using the drug due to the possibility of potential fetal harm. 

The agency also counsels sexually active males to use reliable contraception during treatment and for three months after completion of the course of treatment.