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. Author manuscript; available in PMC: 2015 Aug 1.
Published in final edited form as: Anesthesiology. 2014 Aug;121(2):290–301. doi: 10.1097/ALN.0000000000000268

Table 1.

Octanol:Buffer Partition Coefficients and Subunit-Dependent EC50s for Direct Activation of γ-aminobutyric acid type A (GABAA) receptors

Sedative-Hypnotic Octanol:Buffer Partition Coefficient GABAA Receptor EC50#
β3 Subunit (μM)		 GABAA Receptor EC50#
β1 Subunit (μM)		 Subunit Selectivity Ratio*
R-Etomidate 731 ± 72 1.83 ± 0.28 50.17 ± 0.83 27.4 ± 4.2
S-Etomidate 711 ± 90 57.0 ± 5.1 1080 ± 230 18.9 ± 4.4
Cyclopropyl Etomidate 458 ± 45 67.6 ± 8.1 1590 ± 140 23.5 ± 3.5
Dihydrogen Etomidate 388 ± 32 161 ± 13 400 ± 28 2.48 ± 0.27
#

EC50 = Drug concentration that produces the half-maximal effect.

*

Subunit Selectivity Ratio = EC50 β1 subunit/EC50 β3 subunit.

Hill coefficients for GABAA receptor EC50s ranged from 0.64 to 0.92.

For every drug, the EC50 for direct activation was significantly lower in receptors containing β3 subunits (i.e. α1(L264T)β3γ2L GABAA receptors) than β1 subunits (i.e α1(L264T)β1γ2L GABAA receptors).

All reported errors are Standard Deviations.