Table 4

In vivo estimates of the relative efficacy (e _PD) and receptor affinity (K _PD) for flunitrazepam, midazolam, oxazepam, and clobazam on the basis of the mechanism-based pharmacodynamic model, and the in vitro estimates of benzodiazepine receptor affinity (K _i) as determined in a benzodiazepine receptor preparation

Benzodiazepine	e_PD	K_PD	K_PD,u	K_I	RatioK_PD,u/K_i
		ng/ml	ng/ml	ng/ml
Flunitrazepam	1	21 ± 2.1	3.2	7.0	0.46
Midazolam	0.87 ± 0.03	43 ± 6.0	1.6	4.9	0.33
Oxazepam	0.90 ± 0.04	411 ± 49	36	86	0.42
Clobazam	0.79 ± 0.03	782 ± 86	242	350	0.69

K _PD,u reflects the in vivo receptor affinity based on unbound drug concentrations.