Abstract

Morphine, codeine, dilaudid, and desomorphine inhibit the activity of cholinesterase from the following sources: human, dog or rabbit serum, and human or rabbit brain. The degree of inhibition varies with the source of the enzyme, which might account for the selective action of these drugs on physiological systems. The inhibition is in part competitive and in part non-competitive, judging by the relative reaction velocity at different substrate concentrations. The affinity of the alkaloids for the enzyme in human serum is as great (dilaudid) or greater (codeine, morphine and desomorphine) than the affinity of the enzyme for acetylcholine.