TABLE 1

Derived kinetic parameters of R- and S-lorazepam glucuronidation by human liver microsomes

Data are modeled using the substrate inhibition equation.

	R-Lorazepam				S-Lorazepam
Liver	K_m	V_max	K_si	CL_int^{^a}	K_m	V_max	K_si	CL_int^{^a}
	µM	pmol/min/mg protein	µM	µl/min/mg	µM	pmol/min/mg protein	µM	µl/min/mg
H7	32	5.9	408	0.18	39	5.0	447	0.13
H10	17	5.0	424	0.29	24	9.3	381	0.39
H12	38	9.9	395	0.26	43	13	303	0.30
H13	40	7.1	252	0.18	51	8.7	229	0.17
H40	22	9.1	358	0.41	25	16	395	0.64
Mean ± S.D.	29 ± 8.9	7.4 ± 1.9	367 ± 62	0.26 ± 0.08	36 ± 10^*	10 ± 3.8	351 ± 76	0.33 ± 0.18
Pooled HLM	37	7.6	263	0.21	37	10	354	0.27

↵^a CL_int calculated as V_max/K_m.
↵* P < 0.05.