Combining the antiviral remdesivir or molnupiravir with the experimental drug brequinar blocks the reproduction of the SARS-CoV-2 virus, that causes COVID-19, in lung cells and in mice, according to a study. The research, published recently in the journal Nature, suggests that these drugs are more potent when used in combination than individually. Though they have not yet been tested in clinical trials, the combinations of drugs identified in the study have the potential to become very promising COVID-19 treatments, the researchers said. "Identifying combinations of antivirals is really important, not only because doing so may increase the drugs' potency against the coronavirus, but combining drugs also reduces the risk of resistance,” said study principal investigator Sara Cherry, a professor at the University of Pennsylvania, US.