Table 3.

Examples of representative imidazolone (12–17) and pyrazolone derivatives (18, 19) developed by Chiesi Farmaceutici S.p.A.

Compound	R1	R2	IC50 (nM)a	Reference
12		H	< 1	[143]
13		H	< 1	[143]
14		H	< 1	[143]
15		H	< 1	[143]
16			< 1	[144]
17			< 1	[144]
18			< 1	[144]
19			< 1	[144]

^aThe results are means of two independent experiments, each performed in duplicate (HNE enzyme assay).