Table 1

Kinetic analysis of CYPs 3A4 and 2B6 towards N-dechloroethylation of IFA enantiomers

Supersomes	IFA Enantiomers	DCl Metabolites	K_m^1-a	V_max	V_max/K_m
CYP3A4^1-b	R	R2	2.3 ± 0.4	10.7 ± 1.9	4.8 ± 0.2
		S3	0.9 ± 0.1	2.1 ± 0.1	2.4 ± 0.2
	S	S2	0.7 ± 0.2	1.6 ± 0.7	2.1 ± 0.3
		R3	1.1 ± 0.2	35.3 ± 12.0	31.0 ± 5.0
CYP2B6	R	R2	0.5 ± 0.3	0.8 ± 0.2	2.0 ± 1.0
		S3	1.9 ± 0.9	8.2 ± 3.1	4.9 ± 1.0
	S	S2	0.9 ± 0.1	11.8 ± 0.2	14.2 ± 0.8
		R3	1.3 ± 0.3	3.4 ± 0.5	2.7 ± 0.2

↵1-a K_m and V_max are expressed in units of mM and nmol/min/nmol P-450, respectively.
↵1-b Supersomes CYP3A4 and CYP2B6 contain human cytochromeb₅ in addition to human P-450 reductase. The molar ratios of b₅/P-450 are 3.6 (CYP3A4) and 2.2 (CYP2B6). The P-450 reductase levels for Supersomes 3A4 and 2B6 were 15 and 30 nmol cytochrome c reduced/min/pmol P-450.