The paper is a review of literature data on interaction of erythrocytic acetylcholinesterase and of mammalian blood serum butyrylcholinesterase with a group of isomeric complex ester derivatives (acetates, propionates, butyrates, valerates, and isobutyrates) of bases and iodomethylates of ephedrine and its enantiomer pseudoephedrine. For 20 alkaloid monoesters, parameters of enzymatic hydrolysis are determined and their certain specificity toward acetylcholinesterase is revealed, whereas 5 diesters of iodomethylates of pseudoephedrine were submitted to hydrolysis only by butyrylcholinesterase. It turned out that 20 alkaloid diesters and 10 trimethylammonium derivatives were uncompetitive reversible inhibitors of acetylcholinesterase and competitive inhibitors of butyrylcholinesterase. The performed for the first time isomer and enantiomer analysis "structure-efficiency" has shown that in most caes it is possible to state the greater complementarity of catalytical surface of enzymes for ligands of pseudoephedrine structure, such differentiation being more often manifested.