Table 2. Median Inhibitory Concentrations of Reference Inhibitor Compounds for CYP 1A2, 2C9, 2D6, and 3A4 Isozyme Assays.

CYP Isozyme	Reference Compound	IC50 μM	S.D.	Literature
1A2	Furafylline	0.96	±0.06	0.5-6.0 μM [27]
2C9	Sulfaphenazole	0.31	±0.04	0.14-0.7 μM [28]
2D6	Quindine	0.04	±0.002	20-150 nM [29, 30]
3A4	Ketoconazole	0.036	±0.004	0.07-8.5 μM [31]

For CYP 1A2 the reference inhibitor compound used was furafylline, for CYP 2C9 with inhibitor control was sulfaphenazole, for CYP 2D6, quinidine was used and for CYP 3A4 ketoconazole was the control compound. The IC50 obtained for each of the control compounds (known inhibitors) were within the limits published in the scientific literature. Each assay was repeated in triplicate.