Nafamostat
Nafamostat is a broad-spectrum, synthetic serine protease inhibitor, with anticoagulant, anti-inflammatory, mucus clearing, and potential antiviral activities. Upon administration, nafamostat inhibits the activities of a variety of proteases, including thrombin, plasmin, kallikrein, trypsin, and Cl esterase in the complement system, and factors VIIa, Xa, and XIIa in the coagulation system. Although the mechanism of action of nafamostat is not fully understood, trypsinogen activation in the pancreas is known to be a trigger reaction in the development of pancreatitis. Nafamostat blocks the activation of trypsinogen to trypsin and the inflammatory cascade that follows. Nafamostat may also decrease epithelial sodium channel (ENaC) activity and increase mucus clearance in the airways. ENaC activity is increased in cystic fibrosis. In addition, nafamostat may inhibit the activity of transmembrane protease, serine 2 (TMPRSS2), a host cell serine protease that mediates viral cell entry for influenza virus and coronavirus, thereby inhibiting viral infection and replication.