As of 2022[update], ensitrelvir had reached Phase III
clinical trials.[11] The Japanese government is reportedly considering allowing Shionogi permission to apply for approval for medical use before the final steps of trials are completed, potentially speeding up the release for sale. This conditional early approval system has previously been used in Japan to accelerate the progression to market of other antiviral drugs targeting COVID-19, including
remdesivir and
molnupiravir.[12] In a study of 428 patients, viral load was reduced, but symptoms were not significantly reduced.[13]
In February 2022, the company sought emergency approval from regulators in Japan.[3][13]
Shionogi announced they had reached a preliminary agreement to supply 1million doses to the Japanese government once the drug is approved. The CEO said they could have capacity to make 10million doses a year.[14]
Ensitrelvir may be effective in treating
smell and taste loss from COVID-19 infection. In a 2023 study, the drug was associated with a 39% reduction in these symptoms.[15]
Society and culture
Legal status
Ensitrelvir was approved for emergency use in Japan in November 2022,[8][3][4] before gaining full approval in March 2024.[1] It was approved in Singapore in November 2023.[16]
Ensitrelvir is being studied for its potential use as
post-exposure prophylaxis (PEP) after SARS-CoV-2 exposure.[19][20] The SCORPIO-PEP trial is a global Phase 3 trial that will evaluate the safety and efficacy of the drug in preventing symptomatic SARS-CoV-2 infection in household contacts of people who tested positive for COVID-19.[20][21][22]
An April 2024 pre-clinical study in a mouse model investigating ensitrelvir demonstrated its potential use as a
pre-exposure prophylactic (PrEP) against developing COVID-19. When administered 24 hours before viral exposure, ensitrelvir significantly increased survival rates, inhibited weight loss, and suppressed viral replication in aged mice.[23]
^World Health Organization (2022). "International nonproprietary names for pharmaceutical substances (INN): recommended INN: list 88". WHO Drug Information. 36 (3): 89.
hdl:10665/363551.
^"Studies Currently Enrolling". University of Kansas Medical Center. Archived from
the original on 28 October 2023. Retrieved 28 October 2023. SCORPIO-PEP is a 28-day study to assess the prevention of COVID-19 infection in those who have been exposed through household contact.