TABLE 1

Kinetic parameters for midazolam, triazolam and alprazolam metabolite formation in CYP3A4 and CYP3A5 baculosomes (mean ± S.E.)

Substrate	Pathway	Enzyme	V_max	K_m or K_s	α	β	CL_int or CL_max
			pmol/min/pmol P450	mM			ml/min/nmol P450
Midazolam	1′-Hydroxy	CYP3A4	1.96 ± 0.08	2.69 ± 0.53			728
		CYP3A5	6.7 ± 0.5	10.7 ± 1.2		0.22 ± 0.04	626
	4-Hydroxy	CYP3A4	2.52 ± 0.16	29 ± 5			86.3
		CYP3A5	0.52 ± 0.09	12.1 ± 2.7		0.45 ± 0.13	43
Triazolam	1′-Hydroxy	CYP3A4	1.40 ± 0.03	16.5 ± 1.4			84.8
		CYP3A5	2.63 ± 0.13	25.1 ± 4.3			104.8
	4-Hydroxy	CYP3A4	3.70 ± 0.16	186 ± 38	0.29 ± 0.11		21.7
		CYP3A5	4.02 ± 0.22	150 ± 31	0.33 ± 0.10		27.8
Alprazolam	1′-Hydroxy	CYP3A4	0.13 ± 0.005	144 ± 51	0.27 ± 0.08		1.04
		CYP3A5	1.28 ± 0.15	226 ± 34	0.45 ± 0.18		5.7
	4-Hydroxy	CYP3A4	2.48 ± 0.07	187 ± 18			13.3
		CYP3A5	1.96 ± 0.09	338 ± 61	0.36 ± 0.08		6.03