Sivelestat (ONO-5046) is a potent neutrophil elastase inhibitor. It acts as a substrate-competitive, and highly specific inhibitor of neutrophil elastase (IC50 = 19-49 nM in rat, rabbit, hamster, human, and mouse leukocyte elastase). Sivelestat displays >100-fold greater selectivity over pancreatic elastase (IC50 = 5.6 μM). It does not inhibit trypsin, thrombin, plasmin, kallikrein, chymotrypsin, and cathepsin G even at concentrations as high as 100 μM. MW: 434.46. Purity ≥97% by HPLC