TABLE 1

Reported inhibition kinetics for BG and DHB toward CYP3A4 catalytic activity in various enzyme systems


CYP3A Substrate

Enzyme Sourcea

IC50

K1

kinact

Reference
BG
DHB
BG
DHB
BG
DHB
μM min −1
Nifedipine (5 μM) HLM 1.5 0.65 Tassaneeyakul et al. (2000)
Nifedipine (100 μM) 40 5.6 0.08 0.06
Omeprazole (5 μM)
Sulfoxidation 1.0 0.25
3-Hydroxylation 1.7 0.3
Testosterone (0.2 mM) HLM 1.0 0.45 Ohnishi et al. (2000)
cDNA-expressed CYP3A4 >20 1.0
Testosterone (0.2 mM) Reconstituted 7.7 0.3 He et al. (1998)
CYP3A4 59 0.16 Schmiedlin-Ren et al. (1997)
Testosterone (0.2 mM) HLM 22 2 Guo et al. (2000)
Saquinavir (3 μM) HLM 3.1 1.7 Eagling et al. (1999)
HLM 0.74 0.33
Midazolam (50 μM) HLM >100 4.7 Greenblatt et al. (2003)

HLM
25
0.3





  • HLM, human liver microsomes.

  • a The inhibitor was preincubated with the enzyme source before the substrate was added.