Abstract

The kinetics of the hepatic microsomal N-demethylation and binding of enantiomerically related drugs has been studied. The Michaelis constants for metabolism did not differ between any of the enantiomers studied, whereas the maximal velocities differed between propoxyphene and methorphan enantiomers but not in the case of carbinoxamine enantiomers. Both the spectral binding constants and maximal spectral changes were different between propoxyphene enantiomers but not between carbinoxamine enantiomers; levomethorphan elicited a difference spectrum with microsomes, but dextromethorphan did not.