TABLE 3

Comparison of the kinetic constants of reversible and time-dependent inhibition (TDI) determined from manual and automated assays for troleandomycin (TAO), mifepristone (MIF), and erythromycin (EMC)

The reversible inhibition IC50 values derived from the TDI data were calculated as described in Fig. 8. The reversible inhibition screen was performed as described by Weaver et al. (2003). Manual and automated experiments were n = 3 with CV values less than 10% for KI and kinact.




Substrate

TAO

MIF

EMC
Manual kinact (min-1) Midazolama 0.25 0.09 0.16
Automated kinact (min-1) Midazolama 0.12 0.08 0.12
Manual KI (μM) Midazolama 0.47 0.85 9.5
Automated KI (μM) Midazolama 0.26 0.61 8.8
Manual kinact (min-1) Midazolamb 0.16 0.07 0.09
Manual kinact (min-1) Testosteroneb 0.06 0.06 0.06
Manual KI (μM) Midazolamb 0.8 2.8 8.3
Manual KI (μM) Testosteroneb 0.7 4.1 9.5
Reversible IC50 derived from the TDI experiment (μM) Midazolam 0.3 1.5 8
IC50 value estimated from the reversible P450 inhibition screen (μM)
Midazolam
0.5
0.7
8
  • a Incubations contained 25 pmol CYP3A4/ml.

  • b Incubations contained 1250 pmol CYP3A4/ml.