Lambrecht_1982_Arzneimittelforschung_32_130

In the course of investigations of structure and conformation-activity relationships of heterocyclic acetylcholine analogues, the cholinergic properties of the tertiary (7) and quaternary (8) 4-acetoxyquinuclidine were studied. Both esters have no affinity when tested at the nicotinic receptor, and they are not hydrolyzed by acetylcholinesterase. In the guinea-pig ileum and atrium assay, the heterocyclic analogues 7 and 8 demonstrate agonistic properties, but their potency is three to four orders of magnitude lower than that of acetylcholine. Stereochemical restrictions seem to be responsible for the weak muscarinic potency of both quinuclidine analogues.