RT Journal Article SR Electronic T1 Species differences in the stereoselective hydrolysis of esmolol by blood esterases. JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 425 OP 428 VO 16 IS 3 A1 C Y Quon A1 K Mai A1 G Patil A1 H F Stampfli YR 1988 UL http://dmd.aspetjournals.org/content/16/3/425.abstract AB The stereoselective hydrolysis of esmolol was examined in blood from several species including humans. Blood esmolol esterase activity was in the order of guinea pigs greater than rats greater than rabbits greater than dogs greater than rhesus monkeys greater than humans. Dog and rat blood esterases hydrolyzed the (-)-enantiomer of esmolol faster than the (+)-enantiomer whereas rhesus monkey, rabbit, and guinea pig blood esterases hydrolyzed the (+)-enantiomer faster. Human blood esterases did not demonstrate stereoselectivity. Dog liver esterases also showed stereoselectivity towards the (-)-enantiomer but dog skeletal muscle esterases did not. Studies in mongrel dogs indicated that during esmolol infusions the concentration ratio of (-)-esmolol/(+)-esmolol was approximately 0.85. After termination of the esmolol infusion the (-)/(+) concentration ratio continuously decreased until (-)-esmolol was no longer quantifiable. These results indicate that stereoselective hydrolysis of esmolol occurs in vitro and in vivo.