B. Bethanechol

Bethanechol is an unsubstituted carbamoyl ester, structurally related to ACh, in which the acetate is replaced by carbamate, and the choline is methylated. Hence, it is not hydrolyzed by AChE (due to the esterifi cation of carbamic acid), although it is inactivated through hydrolysis by other esterases. It lacks nicotinic actions (due to the addition of the methyl group) but does have strong muscarinic activity. Its major actions are on the smooth musculature of the bladder and GI tract. It has about a 1-hour duration of action.