Drug Acting on G.I. System
Cholinergic
Anticholinergics
Fluid and Electrolyte therapy
Cholinergic Drug
Parasympathomimetic or cholinomimetics
Stimulate parasympathetic nervous system in same manner as
does acetylcholine
May stimulate cholinergic receptors directly or slow
acetylcholine metabolism at synapses (Affect the enzyme acetylcholinesterase)
Useful in treating Alzheimer’s disease, Myasthenia gravis and
to treatment atony of the smooth muscle of the GI system or urinary system.
GI effects
Acetylcholine stimulates cholinergic receptors in the gut to
promote normal secretory and motor activity
Cholinergic activity in the gut will increase peristalsis
and facilitates movement of flatus and feces.
The secretory functions of the salivary and gastric glands
also stimulated.
Increased tone and contractility in GI smooth muscle,
relaxation of sphincters, increased salivary gland and GI secretions.
Anticholinergics
Also called cholinergic blocking agents or parasympatholytics
Again, focus is on the parasympathetic nervous system
Parasympathetic system acts as a resting and reparative
function Functions include digestion, excretion, cardiac decelertion, and
anabolism and near vision.
Most anticholinergic drugs interact with the muscarinic
receptors in the brain, secretory glands, heart, and smooth muscle.
A few can also affect the nicotinic receptors.
Glycopyrrolate (Robinul) is an example
Mechanism of action:
Act by occupying receptor sites at parasympathetic nerve endings,
thereby leaving fewer receptor sites free to respond to acetylcholine.
Distribution of receptors is broad so effect of anticholinergics
will be diffuse.
Helpful in treating irritable colon or colitis.
Useful in gastritis, pylorospasm and ulcerative colitis as
they slow motility.