Local anesthetic effect of carbisocaine and its enantiomers.

The optically active isomers of carbisocaine [1-methyl-2-diethylaminoethyl ester of 2-(n)-heptyloxycarbonilic acid] were prepared. The blocking activity of equimolar concentrations of the carbisocaine and its corresponding enantiomers was tested on isolated rat sciatic nerves. There were no significant differences between the anesthetic action of racemic form and enantiomers, however, lower activity for the (--)-enantiomer was observed. The results may indicate negligible stereoselectivity of action of highly lipophilic local anesthetic carbisocaine in the excitable membrane.