TABLE 6

Enzyme kinetics for cytochrome P450 CYP3A catalyzed reactions in recombinant human CYP3A4 and CYP3A5^{^a}

	CYP3A4			CYP3A5			CL_int Ratio
	K_M ± S.E.	V_max ± S.E.	CL_int	K_M ± S.E.	V_max ± S.E.	CL_int	(3A5/3A4)
Alprazolam
1′-Hydroxylation	55 ± 9	4.1 ± 0.2	0.074	40 ± 8	6.1 ± 0.2	0.15	2.0
4-Hydroxylation	130 ± 17	54 ± 3	0.41	100 ± 10	24 ± 7	0.24	0.59
Midazolam
1′-Hydroxylation	1.8 ± 0.4	3.9 ± 0.3	2.2	0.84 ± 0.17	23 ± 1	28	12
4-Hydroxylation	7.8 ± 0.9	2.9 ± 0.2	0.38	7.5 ± 1.0	5.0 ± 0.2	0.67	1.8
Triazolam
1′-Hydroxylation	9.4 ± 1.0	24 ± 1	2.6	1.7 ± 0.9	17 ± 0	10	3.8
4-Hydroxylation	40 ± 6	41 ± 1	1.0	52 ± 3	28 ± 0	0.52	0.52
Testosterone
6β-hydroxylation	14 ± 2	60 ± 2	4.4	57 ± 5	140 ± 5	2.3	0.52
Atazanavir
Phenyl p-hydroxylation	2.5 ± 0.6	0.094 ± 0.006	0.038	3.9 ± 0.8	0.75 ± 0.04	0.19	5.0
t-Butyl hydroxylation	2.5 ± 0.4	0.38 ± 0.10	0.15	5.3 ± 1.2	1.9 ± 0.1	0.36	2.4

CL_int, intrinsic clearance.
↵^a Units: K_M: µM; V_max: nmol/min/nmol; CYP CL_int: ml/min/nmol;