Cholinergics and Anticholinergics on the Parasympathetic Nervous System

The Parasympathetic Nervous System (PNS) is a part of the autonomic nervous system and compliments the sympathetic nervous system (SNS). It promotes normal maintenance of the body, utilizes and rids of waste, and increases secretions and mobility of the digestive tract. Basically, it is used for "resting and digesting."

Cholinergic Agents (Wet as the ocean)

Cholinergic drugs are also known as cholinergic agonists. They mimic the effects of acetylcholine and stimulate the parasympathetic nervous system.

Mechanism of Action:
Direct-acting cholinergic agonists
-Bind to cholinergic receptors, activating them.
Indirect-acting cholinergic agonists
-Inhibit the enzyme cholinesterase which breaks down acetylcholine (these causes an increase in acetylcholine at the receptors).

Why Use Direct-Acting Cholinergic Drugs?
*Glaucoma: Reduces intraocular pressure

Which includes the drugs: Acetylcholine, carbachol, pilocarpine (poor oral absorption used topically).

Atony and Neurogenic Bladder: Increases tone and motility of bladder and GI tract.
Which includes the drug: Bethanechol (Urecholine) (PO or SUB Q. Urination should occur within 60 minutes of administration).

Why Use Indirect-Acting Cholinergic Drugs?
*Myasthenia gravis: Help with skeletal muscle contraction and inhibits the breakdown of acetylcholine.

Which include the drugs: Pyridostigmine and Physostigmine.
Physostigmine is used as an antidote for anticholinergic poisoning (atropine) and common pesticide poisoning.

*Alzheimer's Disease: Prevents cognitive deterioration and increases concentrations of acetylcholine in the brain.
Which includes the drug: Donepezil (Aricept). (Not a cure and may take up to 6 weeks to work).

Contraindications (WHEN NOT TO USE):
GI or GU tract obstruction
Parkinsons Disease

Side Effects:

Side Effects:
wikispace_pics_2.jpgBradycardia, hypotension, conduction abnormalities
Headache, dizziness, convulsions wikispace_3.jpg
wikispace_4.jpgAbdominal cramps, increased secretions, nausea, vomiting

Increased bronchial secretions, bronchospasms wikispace_6.jpg

Other: Lacrimation, sweating, salivation, loss of binocular accommodation, miosis (pupil constriction)

What drugs should you avoid when taking cholinergics?
*Caution with other cholinergic agents-has additive effects

What are signs and symptoms of toxicity?
Urinary incontinence
Gastrointestinal cramps

Nursing Implications
-Medications should not be stopped abruptly and taken as ordered.
-Assess for presence of GI or GU obstructions, asthma, peptic ulcer disease, or coronary artery disease.
-Patients with myasthenia gravis should take their medication 30 minutes before eating to help improve chewing and swallowing.
-Monitor for therapeutic effects

Anticholinergic Agents


"Dry as the Desert"

How do they work?

Anticholinergic drugs block or inhibit the actions of acetylcholine (ACh) in the PNS

*Also called cholinergic blockers, parasympatholytics, or antimuscarinics

Mechanism(s) of Action
*Blocks and/or competes with ACh receptors
*Inhibits nerve transmission at ACh receptors
-->When ACh is blocked, the PNS is inhibited and the SNS is able to take over

Drug effects (Therapeutic effects), Indications (Why take these drugs?), and Side Effects

Drug Effectsddddddddddddddddddddd
Side Effectsddddddddddddddddd
*Lowers HR (in small doses)
*Increases HR (in large doses)

*Increased HR, dysrhythmias
*Decreases bronchial secretions
*Dilates bronchial airways
*Exercise-induced bronchospasms
*Chronic bronchitis
*Decreased bronchial secretions
*Decreases muscle rigidity and tremors (in small doses)
*Increases drowsiness, disorientation, and hallucinations (in large doses)
*Muscle rigidity
*Drug-induced EPS (and tardive dyskinesia)
*Excitation, restlessness, irritability, disorientation, hallucinations, and delirium
*Relaxes smooth muscle of GI tract
*Decreases intestinal and gastric secretions
*Decreases motility and peristalsis

*Decreased salivation, GI motility, and gastric secretions
*Relaxes detrussor muscle
*Increases constriction of internal sphincter
*Urinary retention
*Overactive bladder
*Urinary incontinence
*Reflex neurogenic bladder
*Urinary retention
*Decreases bronchial secretions, salivation, and sweating

*Decreased sweating
*Dilates pupils and increases ocular pressure
*Decreases accomodation

*Same as Drug Effects

Contraindications (Do not use if you have...)
*Drug Allergy
*Narrow-angle glaucoma
*Acute asthma
*Myasthenia gravis
*Respiratory distress
*Acute cardiovascular instability
*GI/GU obstructions

Anticholinergic drugs can be "natural", like Scopolamine and Atropine, or synthetic like Benztropine, Dicyclomine, Oxybutynin, Tolteradine, and Glycopyrrolate.

*primarily used for CV disorders and sinus node dysfunction
*symptomatic 2nd degree heart block
*decreases secretions from nose, mouth, pharynx and bronchi
*relaxes smooth muscle in bronchi and bronchioles, leading to bronchodilation and a decreased airway resistance
*Reversal drug for CHOLINERGIC overdose
*Antidote for Atropine overdose is Physostigmine

Benztropine (Cogentin)
*Antiparkonsonian drug
*Decreases muscle rigidity

Dicyclomine (Bentyl)
*Treats: peptic ulcer disease, irritable bowel disease, and GI hypersecretory states

Glycopyrrolate (Robinul) and Atropine
*Used preoperatively to decrease secretions (respiratory, GI, and salivation) during surgery

*Transdermal patch placed behind the ear
*Prevention of motion sickness
*Corrects imbalance of ACh and norepinephrine in the brain

Tolteradine (Detrol) and Oxybutynin (Ditropan)
*Treats incontinence and overactive bladder
*Relaxes detrussor muscle and increases constriction of the internal sphincter
*Treats reflex neurogenic bladder (Oxybutynin only)

Drug Interactions (Do not use with...)
*Antihistamines, phenothiazines, MAOI's and TCA's

Nursing Impications
*Assess for: BPH, glaucoma, MI, tachycardia, allergies, hiatal hernia and GI/GU obstruction(s)
*Sensitivity to light and dry mouth may occur
*High risk of heat stroke in geriatric patients, so limit higher temperatures, physical exertion, and/or exercise, and stress fluid and salt intake

Report the following conditions to your physician: Urinary hesitancy and/or constipation, palpitations, tremors, confusion, sedation or amnesia, excessive dry mouth and fever

Match the indication with the drug used to treat it!

1.) Alzheimer's Disease
2.) Cardiac and Respiratory Disorders
3.) Atony and Neurogenic Bladder
4.) Prevent motion sickness
5.) Myasthenia gravis
6.) Peptic ulcer & IBD
7.) Glaucoma
8.) Parkinson's Disease
9.) Decrease secretions preoperatively
10.) Treat reflex neurogenic bladder (spinal cord injury)
11.) Incontinence-overactive bladder

a.) Glycopyrrolate (Robinul), Atropine
b.) Donepezil (Aricept)
c.) Acetylcholine, carbachol, pilocarpine
d.) Benztropine (Cogentin)
e.) Dicyclomine (Bentyl)
f.) Oxybutynin (Ditropan)
g.) Scopolamine
h.) Bethanechol (Urecholine)
i.) Atropine
j.) Pyridostigmine, Physostigmine
k.) Tolterodine (Detrol), Oxybutynin (Ditropan)

Reference: Anne, L., Rainforth, S., Harrington, S., & S., J. (2010). Pharmacology and the Nursing Process. St. Louis: Mosby.