By Fineline Cube 
Shionogi announced on April 1, 2025, the initiation of a rolling New Drug Application (NDA) submission to the US Food and Drug Administration (FDA) for its investigational oral antiviral drug ensitrelvir. This submission is for the post-exposure prophylaxis following contact with COVID-19 patients. Ensitrelvir has been granted Fast Track designation by the FDA in 2025 for this prophylactic use and in 2023 for the treatment of COVID-19.
Global Regulatory Progress
In November 2022, ensitrelvir received emergency use authorization in Japan, followed by formal approval in March 2024 under the brand name Xocova. The drug was approved for marketing in Singapore through a special access route in 2023. In 2025, Shionogi submitted a supplemental NDA in Japan for ensitrelvir for post-exposure prophylaxis of COVID-19. Currently, the drug is under regulatory review for marketing approval in Taiwan. Outside of Japan and Singapore, ensitrelvir remains in the research phase.-Fineline Info & Tech