. Author manuscript; available in PMC: 2009 Jun 24.

Published in final edited form as: Bull Anesth Hist. 2003 Jul;21(3):1–passim. doi: 10.1016/s1522-8649(03)50031-2

Table 2.

Experimental Observations in Conflict with Unitary Theories of Anesthesia

Experimental Observation	First year described

Barbiturates
Stereoisomers have different anesthetic potencies⁷⁸	1934
Convulsant barbiturates described⁷⁹	1940

Chloral hydrate
Anesthetic properties inconsistent with Meyer-Overton hypothesis¹⁴	1901
Metabolized to trichloroethanol, which is the active anesthetic compound in mammals²²,²⁵	1948

Chloraloses
α-Chloralose lack anesthetic activity¹⁴	1901
Arabinochloraloses show anesthetic potency differences between both optical and structural isomers¹⁶	1940

Etomidate
Stereoisomers have different anesthetic potencies⁸⁰,⁸¹	1975
Stereoisomers equally soluble in lipid bilayers⁸¹	1998

Flurothyl
Convulsant properties described³⁷,³⁸	1957
Isomer ‘iso-flurothyl’ is anesthetic³⁹,⁴⁰	1967

Isoflurane
Stereoisomers have different anesthetic potencies⁸²–⁸⁴	1992
Stereoisomers equally soluble in lipid bilayers⁸⁵	1991

Propofol (2,6-diisopropylphenol)
Alkylphenol analogs such as 2,6-di-tert-butylphenol inactive⁸⁶–⁸⁹	1980

Steroid anesthetics
Inactive congeners of anesthetic steroids described⁹⁰,⁹¹	1965
Stereoselectivity of steroid anesthetics shown⁹²	1996

Volatile non-immobilizers
Highly lipid-soluble volatile alkanes and ethers found which lack anesthetic effects⁹³–⁹⁵	1994