TABLE 1

Summary of incubation conditions for cytochrome P450 marker assays Assay conditions were as described under Materials and Methods. Results are means of two to four independent experiments. Control activity without inhibitor was set at 100%.


P450

Reaction

Substrate Concentration

Control Inhibitor

Inhibitor Concentration

Residual Activity
μM μM %
1A2 7-Ethoxycoumarin O-deethylation 10 Furafylline 10 8.4
2A6 Coumarin 7-hydroxylation 200 Diethyldithiocarbamate 100 30.7
2B6 Bupropion hydroxylation 50 Triethylenethiophosphoramide 10 11.8
2C8 Verapamil O-demethylation 100 Ketoconazole 100 N.D.
2C9 (S)-Mephenytoin N-demethylation 10 Sulfaphenazole 10 34.7
2C19 (S)-Mephenytoin 4'-hydroxylation 200 Ketoconazole 100 41.7
2D6 Propafenone 5-hydroxylation 2 Quinidine 5 40.7
2E1 7-Ethoxycoumarin O-deethylation 200 Diethyldithiocarbamate 1 1.2
3A4
Verapamil N-demethylation
100
Ketoconazole
100
18.2
  • N.D., not detectable.