A deuterated nitrogen-containing heterocyclic carboxamide derivative represented by the general formula or a salt thereof: [wherein D represents a deuterium atom and X represents a halogen atom] exhibits excellent pharmacokinetics and the like, such as the decrease of a metabolic rate and the maintenance of a high blood concentration, and is useful as an antiviral agent.由以下通式所表示的氘化含氮雜環羧醯胺衍生物或其鹽:[其中D表示氘原子;及X表示鹵素原子]呈現優良的藥物動力學等,如降低新陳代謝速率及維持高血液濃度,且可用作為抗病毒劑。
