Accordingly, we present valuable information regarding the degradation of pyrazine antiviral RNA-analog-drugs by O2 •-, which is assumed to be important to manage the concentrations of antiviral drugs in an inflamed organ. It is hoped that this study provides an insight into the antiviral drugs that are not easily metabolized, thereby expanding the point to consider drug design and utility, such as enhancement of net pharmacological activity and reduction of side effects associated with less dosage.