TABLE B-4 Relative Lipophilicity of Benzodiazepines

Source and Drug

HPLC Retention Indexa

Concentration in Whole Brain/Unbound Concentration in Serum

Inhibitory Constant Ki

Arendt et al. (1987)

Halcion

0.6

19.5

0.4b

Diazeparn

1.0

26.05

9.57b

Desmethyldiazepam

0.8

22.18

5.58b

Alprazolam

0.5

2.62

4.4b

Lorazepam

0.5

16.0

1.6b

Midazolam

1.5

33.91

0.4b

Miller et al. (1988)

Flurazepam

56.8c

8.2

12.7b

Desalkylflurazepam

29.1c

7.0

0.85b

Sethy and Harris (1982) (flunitrazepam displacement, ''brain" pellet)

Halcion

 

 

0.76d

Alpha-hydroxytriazolam

 

 

0.92d

4-Hydroxytriazolm

 

 

0.32d

a Relative to diazepam. HPLC, high-pressure liquid chromatography.

b Units of Ki (inhibitory constant) are IC50/1 + S/Kd where IC50 is the 50% inhibitory concentration and S is the flunitrazepam concentration.

c In minutes.

d In nanomolar.



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