ASC11 + ritonavir

ASC11 + ritonavir is an oral combination of **ASC11**, a direct-acting small molecule inhibitor of the SARS-CoV-2 main protease (**3-chymotrypsin-like protease, 3CLpro**), and **ritonavir**, a pharmacokinetic enhancer. ASC11 was discovered and developed by Ascletis and functions by inhibiting 3CLpro, an essential viral protease required for coronavirus replication. Ritonavir, originally developed as an HIV protease inhibitor, is included at a low dose to inhibit cytochrome P450 3A enzymes, thereby boosting ASC11 plasma concentrations and prolonging its antiviral activity. The main indication under study is **COVID-19**. Preclinical and early clinical research demonstrated ASC11 has greater in vitro potency than other 3CLpro inhibitors, including nirmatrelvir. Clinical development is ongoing, with Ascletis conducting Phase I trials to evaluate safety, tolerability, pharmacokinetics, and optimal need for ritonavir boosting in healthy subjects[1][2][4][6].