Drug repurposing: a promising drug discovery strategy for the treatment of emerging epidemic infectious disease.

Epidemic refers to a disease when the occurrence level exceeds expected standards (generating an epidemic phenomenon), in which infectious diseases pose a major challenge to global health. The concept of epidemiology arises with infectious diseases, which can infect many people within a certain period and lead to a pandemic. Especially in the face of sudden epidemics, time is of the essence. In such urgent scenarios, the time required for traditional drug discovery is often prohibitive, given its inherently long timelines, high costs, and frequent failures. Drug repurposing strategies, mainly divided into experimental and computational approaches,which involves identifying new therapeutic applications for already approved pharmaceuticals, have gained substantial attention as a time-efficient and cost-effective alternative. In light of this, the present review provides a comprehensive overview of the various approaches to drug repurposing for the treatment of emerging epidemic infectious diseases, the majority of which are sudden epidemics caused by viruses. In addition, we discuss the challenges faced by repurposing and propose innovative approaches to address these challenges to better achieve the successful translation of drug repurposing into clinical applications and maximize the therapeutic value of drugs.