Covid-19: Warning that MSD’s pill could risk creating virus resistance

RIO DE JANEIRO, BRAZIL – Although it has not yet been cleared by regulators, Merck’s molnupiravir pill has been celebrated as a potential breakthrough, because it could be relatively cheap and easy to manufacture, does not require infusion, and has been shown to reduce the risk of hospitalization in a trial.

However, it may need to be combined with other drugs to prevent resistance, Wellcome Foundation director Jeremy Farrar said.

Resistance occurs when viruses and bacteria evolve to halt or defeat the drugs’ attack mechanism. It is an ongoing concern with antivirals and antibiotics and has been seen in treatments for Covid-19, such as Eli Lilly’s antibody therapy. Farrar believes that Merck’s pill would be no exception, despite optimism that it could be a new weapon to fight the pandemic.

PREVIOUS EXPERIENCE INDICATE MUTATIONS ARE RARE

While being always a concern for infection drugs, the likelihood of it becoming a serious problem for molnupiravir seems to be low, said Nick Kartsonis, senior vice president of clinical research for infectious diseases and vaccines at Merck Research Labs. Previous experiences with other viruses have shown that the evolution of resistant mutations is rare, he said.

The course of treatment is short, which means that viruses have little chance of evolving into resistant forms. Another reason lies in the drug’s mode of action. Developed by researchers at Emory University and other academic centers and subsequently licensed by Ridgeback Therapeutics, a Merck partner, molnupiravir works by introducing errors into the genetic material of the coronavirus. Errors are replicated until the virus is destroyed.