Kinetic parameters for the in vitro effect of various CYP3A4 substrates on testosterone in human lymphoblast-expressed CYP3A4, generated by multisite kinetic model approach (mean ± S.E.) The kinetic parameters were determined using kinetic model (n = 25-30) defined by equation 4, β (Kp from SES) = 2. Vmax is equivalent to 2Kp[E]t, in which [E]t is the total enzyme concentration (Segel, 1975).
CYP3A4 Modifier | Vmax | Ks | Ki | α | δ |
|---|---|---|---|---|---|
| pmol/min/pmol of P450 | μM | μM | |||
| NIF | 5.5±0.3 | 150±35 | 9.5±3.5 | 0.07±0.02 | 0.14±0.06 |
| FEL | 10.1±0.5 | 173±22 | 37.1±7.4 | 0.14±0.04 | 0.04±0.02 |
|
MDZ
|
10.3±0.5
|
128±19
|
23.1±5.4
|
0.15±0.05
|
0.08±0.03
|