Table 6.

Inhibition of the specific cytochrome P450 isoforms by imepitoin

	Inhibition of the specific cytochrome P450 isoform IC50 [μm]
Isoenzyme	1A1	1A2	2A6	2C9	2C19	2D6	3A4
Binding site							BQ	BFC	DBF
Standard inhibitor	0.231	0.772	0.493	0.364	2.83	0.025	0.401	0.111	0.051
Imepitoin	55	n.e.	n.e.	n.e.	n.e.	n.e.	n.e.	n.e.	n.e.

Inhibiton of specific human cytochrome P450 isoforms in vitro. Displayed are mean IC₅₀ values for each enzyme. For human CYP3A4, 3 different binding sites are reported which were individually addressed by the specific ligands BQ (benzyloxyquinoline), BFC (7-benzyloxy-4-(trifluoromethyl)-coumarin), and DBF (dibenzylfluorescein). For reference, the following standard inhibitors were tested in the same assay: ¹ketoconazole, ²furafylline, ³tranylcypromine, ⁴sulphaphenazole, and ⁵chinidine. n.e.: no inhibitory effect up to the highest concentration of imepitoin tested (100 μm). Note that data obtained using human enzymes may not be fully representative for dogs due to substantial species differences (Martignoni et al., 2006).