TABLE 4

Comparison of IC50 values for model P450 inhibitors using fluorescent or conventional probes IC50 (μM) data are mean ± S.D. of three independent experiments (intact P450 cell and human liver microsome assays) or the mean of two experiments (intact human hepatocyte assays).


P450

Inhibitor

Fluorescent probe in Intact P450 Cells

Conventional Probe
Intact P450 Cells
Intact Human Hepatocytes
Human Liver Microsomes
1A2 Furafylline 1.4 ± 0.3a 4.9 ± 1.6 10.6 6.2 ± 1.6
2A6 Methoxalen 0.5 ± 0.2 0.5 ± 0.2 0.6 2.0 ± 1.1
2B6 Tranylcypromine 12.0 ± 2.1 2.7 ± 1.4 N.D. 2.5 ± 1.0
2C8 Quercetin 2.9 ± 1.6 29.5 ± 6.8 N.D. 6.3 ± 1.8
2C9 Sulfaphenazole 0.3 ± 0.1 1.5 ± 0.9 2.6 1.6 ± 1.4
2C19 Tranylcypromine 3.2 ± 1.2 6.0 ± 3.8 22.4 4.4 ± 1.0
2D6 Quinidine 0.5 ± 0.2 0.91 ± 0.66 0.27 0.14 ± 0.06
2E1 Diethyldithiocarbamate 65.8 ± 12.9 33.8 ± 7.8 34.9 6.3 ± 6.0
3A4
Ketoconazole
0.09 ± 0.03
0.09 ± 0.04
0.12
0.08 ± 0.02
  • N.D., not determined.