A potent, selective, reversible, competitive, non-peptide inhibitor of cathepsin G (IC₅₀ = 53 nM and Ki = 63 nM). Acts as a weak inhibitor of chymotrypsin (Ki = 1.5 µM), thrombin, factor Xa, factor IXa, plasmin, trypsin, tryptase, proteinase 3, and human leukocyte elastase (IC₅₀ > 100 µM).