TABLE 2

Examples of recommended in vitro probe substrates, inhibitors, and inducers for CYP3A4 Adapted from Food and Drug Administration Guidance for Industry, September 2006.


Cytochrome P450

Substrates

Inhibitors

Inducers
Preferred
Acceptable
Preferred
Acceptable
Preferred
Acceptable
K m in μM K m in μM K i in μM K i in μM Recommended concentration in μM Recommended concentration in μM
CYP3A4 Midazolam (1–14) Nifedipine (5.1–47)
Testosterone (52–94) Dextromethorphan (133–710) Ketoconazole (0.0037–0.18) Verapamil (10, 24) Phenobarbital (100–2000)
Triazolam (234) Itraconazole (0.27, 2.3) Troleandomycin (17) Rifampin (10–50) Phenytoin (50)
Terfenadine (15) Rifapentine (50)


Erythromycin (33–88)



Dexamethasone (4)