Table 2.

Inhibition of human CYP isoforms by CC12 and cimetidine.

CYP Isoform	Species	% Inh. at 200 nM a or CC12 IC50 (μM) b	Cimetidine Ki (μM)c	Cimetidine Reference c	Tested for 3HCIM Binding?f
2B6	Human	100%a [0.0117]d	---	---	Yes
2C19	Human	0.051b [0.0514]d	14	(Cohen, et al., 2003)	Yes
19A1	Human	88%a [0.1407]d	---	---	Yes
3A5	Human	64%a	---	---	Yes
2A6	Human	62%a	---	---	Yes
1A2	Human	0.120b	86	(Martinez, et al., 1999)	No
2C9	Human	0.128b	140	(Miners, et al., 1988)	Yes
3A7	Human	57%a	---	---	No
3A4	Human	0.217b	82	(Kerlan, et al., 1992)	No
2E1	Human	41%a	---e	---	No
2C8	Human	33%a	---	---	Yes
2D6	Human	0.494b	38	(Madeira, et al., 2004)	No
2C18	Human	N.T.	---	---	Yes
2C11	Rat	N.T.	---	---	Yes
2C6	Rat	N.T.	---	---	Yes
2B1	Rat	N.T.	---	---	Yes

^aPercent inhibition of enzyme activity in the presence of 200 nM CC12 in duplicate.

^bIC₅₀ values were estimated by non-linear regression from pilot studies with three concentrations of CC12 in duplicate.

^cK_i values for cimetidine taken from the literature cited.

^dIC₅₀ values in brackets are from Fig. 6.

^eCYP2E1 has also been reported to be inhibited by cimetidine, however a K_i value has not been reported (Rendic, 2002).

^fAll enzymes tested lacked specific 3HCIM-binding activity. N.T., not tested.