Today, Pioneer Pharmaceutical, a pharmaceutical enterprise located in Nanjing, Jiangsu Province, announced that the innovative anti COVID-19 drug Xiannuoxin (combined packaging of Xianotevir tablets/Ritonavir tablets) jointly developed by the company, Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Wuhan Institute of Virology, was approved by the State Drug Administration (NMPA) in accordance with the special drug approval procedure for emergency review and listing with conditions. It is reported that Xiannuoxin is the first domestic 3CL oral small molecule anti COVID-19 innovative drug. Xiannuoxin is an innovative oral small molecule anti COVID-19 drug. Among them, the combination of Xiannuotvir and low-dose Litonavir, which is a 3CL protease necessary for SARS CoV-2 virus replication, helps to slow down the metabolism or decomposition of Xiannuotvir in the body and improve the antiviral effect. 3CL protease is the main protease found in coronavirus, which is indispensable in the process of virus replication. The 3CL cleavage site is highly conservative, and is not susceptible to virus mutation. It has broad-spectrum anti-coronavirus activity. There is no 3CL homologous protein in human host, with high selectivity and specificity, and low risk of side effects. (Xinhua News Agency)