Ensitrelvir

The clinical demand for oral antiviral therapies for COVID-19 persists continuously along with viral mutations. As an oral 3CL protease inhibitor, ensitrelvir specifically blocks the cleavage process of polyproteins mediated by the 3CL protease of SARS-CoV-2, thereby inhibiting viral replication and assembly. Its indication is the treatment of novel coronavirus infection (COVID-19), and it is applicable to adults and adolescents (12-17 years old, body weight ≥40kg) with mild and moderate COVID-19 who have onset within 5 days and are accompanied by high risk factors for progression to severe disease. As a monotherapy regimen that does not require combination with a pharmacokinetic enhancer, it reduces the risk of drug-drug interactions, and is particularly suitable for elderly patient populations with underlying comorbidities.

At present, the global anti-SARS-CoV-2 drug market still maintains stable demand. In 2023, the global market size of oral anti-COVID-19 drugs was approximately USD 12.8 billion, among which 3CL protease inhibitors accounted for more than 60%. As the first domestically developed oral COVID-19 drug approved in Japan, ensitrelvir achieved sales exceeding JPY 32 billion in the same year after its launch in 2022. Subsequently, along with the advancement of approval in markets such as Southeast Asia and Europe, its market penetration rate continues to rise. At present, the competitive landscape of COVID-19 drugs targeting the 3CL protease in China has not been saturated. With the lower risk of drug-drug interactions, ensitrelvir has differentiated advantages in the medication market for elderly patients.

Ensitrelvir was developed by Shionogi Pharma Co., Ltd. of Japan, and the original research brand name is Xocova. Its core compound patent will expire in Japan in 2041. The compound patent application in China has been rejected, and there is currently no valid compound patent restriction. The dosage form approved by the original research manufacturer is oral tablet, with a specification of 125mg per tablet. The dosing regimen is 3 tablets for the first dose, followed by 1 tablet once daily, for a total treatment course of 5 days. This product has been included in the approved drug catalog of the Ministry of Health, Labour and Welfare of Japan, and has not been listed as a reference listed drug by the FDA. There is currently no approved registration number (status A) for this API in China, and neither imported nor domestic preparations of this product have been approved. (Data as of June 2025, please refer to the official website of CDE for the latest information)

In response to the R&D and quality control requirements for ensitrelvir, CATO can provide a full set of impurity reference standards for this API. Most products are in stock, and orders for in-stock products placed before 16:00 will be shipped on the same day. The products fully comply with the compliance requirements of multiple regulations such as the Chinese Pharmacopoeia and FDA, and can provide stable reference standard support for pharmaceutical enterprises in drug R&D, consistency evaluation and quality control.