Structure-activity studies of cholinergic drugs indicate that:I maximum activity is achieved when the quaternary nitrogen...

Structure-activity studies of cholinergic drugs indicate that:

I maximum activity is achieved when the quaternary nitrogen is three carbons removed from the ester oxo group.

II structures which display a quasi-ring conformation exhibit muscarinic activity.

III one methyl group of the trimethylammonium group can be replaced by an ethyl group with only slight loss of activity.