Table 1. Kinetic parameter values for the in vitro biotransformation of citalopram (CIT) and desmethylcitalopram (DCIT) to DCIT and didesmethyl-CIT, respectively in human and Beagle dog microsomes.

Substrate	Metabolite	Km1	Vmax1	IC1		Km2	Vmax2	IC2	References
Dog liver microsomes*
CIT	DCIT	1.1 ± 0.3	47 ± 3	43		1 006 ± 94	591 ± 28	0.6	this study
CIT	S-DCIT	1.0 ± 0.2	26 ± 1	27		848 ± 69	264 ± 10	0.3
CIT	R-DCIT	1.4 ± 0.5	21 ± 2	15		1 221 ± 161	338 ± 24	0.3
DCIT	DDCIT	0.6 ± 0.2	44 ± 4	73		137 ± 18	155 ± 5	1.0	this study
DCIT	S-DDCIT	0.6 ± 0.1	31 ± 3	52		66 ± 11	55 ± 2	0.8
DCIT	R-DDCIT	0.3 ± 0.2	11 ± 2	37		212 ± 24	105 ± 3	0.5
Human liver microsomes
CIT	DCIT	174	–	–		–	–	–	von Moltke et al. (1999)
CIT	S-DCIT	33.8	20.0	0.6		202	220	1.09	Rochat et al. (1997)
CIT	R-DCIT	17.3	25.0	1.4		185	153	0.83
CIT	S-DCIT	95	433	4.6		–	–	–	Olesen and Linnet (1999)
CIT	R-DCIT	76	300	3.9		–	–	–
CIT	S-DCIT	165	1 007	6.1		–	–	–	von Moltke et al. (2001)
CIT	R-DCIT	256	1 254	4.9		–	–	–
DCIT	S-DDCIT	72	95	1.3		–	–	–	von Moltke et al. (2001)
DCIT	R-DDCIT	108	126	1.2		–	–	–

*Results are presented as means ± SD from six incubations carried out in duplicate

Intrisic clearence (IC) corresponds to the maximum velocity (V_max) divided by the affinity constant, K_m

IC = μl/(min × mg of protein); K_m = μM; V_max = pmol/(min × mg of protein)