The stereospecific effects of isoflurane isomers in vivo.
The anesthetic potency of racemic isoflurane and the optically pure stereoisomers was examined in rats. The (+) isomer was 53% more potent than the (-) isomer (minimum alveolar concentration (MAC) = 1.06 +/- 0.07% vs. 1.62 +/- 0.02%, P < 0.05). MAC for racemic isoflurane was 1.32 +/- 0.03%. Both stereoisomers and the racemic isoflurane produced similar depression of arterial pressure. However, the (+) isomer blunted the cardiovascular response to a painful stimulus to a greater extent than did an equi-MAC dose of the (-) isomer. These are the first data to describe pharmacological differences between stereoisomers of a volatile anesthetic administered in vivo by the conventional route (inhaled) and measuring the clinically relevant index of anesthesia, MAC. These data are consistent with a receptor-mediated anesthetic mechanism by volatile anesthetics.
Lysko
G S
GS
Ohmeda, Pharmaceutical Products Division, Murray Hill, NJ 07974.
Robinson
J L
JL
Casto
R
R
Ferrone
R A
RA
D000762:Anesthesia Recovery Period; D000769:Anesthesia, Inhalation; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D007530:Isoflurane / Q000737:chemistry; D008297:Male; D010146:Pain / Q000517:prevention & control; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism
D007530:Isoflurane