Disclosed is a pharmaceutical compositioncomprising a pyrazine derivative represented by thegeneral formula:(see formula 1)[wherein R1 and R2 independently represent a hydrogenatom or a halogen atom； and R3 represents a hydrogenatom or an amino-protecting group] or a salt thereofand at least one neuraminidase inhibitor. Thepharmaceutical composition is useful for a treatmentincluding the treatment or prevention of influenza.Also disclosed is a method of using these components incombination. The method is useful for a treatmentincluding the treatment or prevention of influenza.
