Parasympathomimetic

Parasympathomimetics (plural of parasympathomimetics ) are drugs that imitate the action of the parasympathetic nervous system . Here is acetylcholine used as a messenger. A distinction is made between direct and indirect parasympathomimetics.

• Direct parasympathomimetics such as carbachol , bethanechol , methacholine , pilocarpine or arecoline act as agonists directly on the muscarinic acetylcholine receptors. The endogenous transmitter acetylcholine would not be suitable for pharmacological therapy, as it is inactivated by the cholinesterases within milliseconds.

• Indirect parasympathomimetics such as physostigmine , rivastigmine , pyridostigmine , neostigmine or distigmine inhibit cholinesterases and thus the breakdown of acetylcholine. The term "indirect parasympathomimetics" is poorly chosen here, however, since acetylcholine occurs as a transmitter in the parasympathetic, sympathetic and motor endplates of the skeletal muscles and acetylcholinesterase is also inhibited there.

Parasympathomimetic effects of these substances include constriction of the pupils , stimulation of the flow of saliva and therapeutic effects in intestinal and bladder atony .

Those cholinesterase inhibitors that also have central nervous effects are used in mild to moderately severe Alzheimer's disease ( rivastigmine , donepezil , galantamine ; tacrine only rarely). Their effectiveness is controversial.

literature

• C.-J. Estler (Ed.): Pharmacology and Toxicology. 4th edition Schattauer, Stuttgart a. New York 1995. pp. 41-46.

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