Pharmacology Chapter 14- Muscarinic Agonists And Antagonists

Front 1

Muscarinic Receptors

Back 1

• decreased secretions from lungs, stomach, intestines, sweat glands
• decrease in HR
•Smooth muscle contraction in bronchi and GI tract
• Miosis (sphincter contraction) and accommodation (ciliary contraction)
• Voiding due to contraction of detrusor muscle and relaxation of trigone and sphincter muscles

Front 2

Cholinergic Drugs are:

Back 2

- Agents that influence the activity of cholinergic receptors
- Most mimic or block the actions of acetylcholine

Front 3

Categories of Cholinergic Drugs and an Example drug for each category

Back 3

Muscarinic Agonists--> Bethanechol

Muscarinic Antagonists--> Atropine

Ganglionic stimulating agents --> Nicotine

Ganglionic blocking agents--> mecamylamine

Neuromuscular blocking agents--> d-Tubocurarine, succinylcholine

Cholinesterase inhibitors--> neostigmine, physostigmine

Front 4

Where are muscarinic receptors located?
M1
M2
M3

Back 4

M1- Salivary glands & CNS

M2- Heart

M3- Salivary glands, bladder:detrusor, GI smooth muscle, Eye: Iris sphincter, Ciliary muscle, & Lacrimal gland

Front 5

What is the response to activation of muscarinic receptors?
M1
M2
M3

Back 5

M1- salivation and enhanced cognition

M2- bradycardia aka decreased HR

M3- salivation, contraction of the detrusor muscle, increased tone and motility of the GI smooth muscle, contraction of they eye and tearing of the eye , contraction of lungs and relaxation, vasodilation, and hypotension for vascular

Front 6

What impact does a blockade of muscarinic receptors have?
M1
M2
M3

Back 6

M1- dry mouth, confusion, and hallucinations

M2- tachycardia or increased HR

M3- dry mouth, relaxation of the detrusor muscle, decreased tone and motility of the GI system (constipation, relaxation of eyes causing blurred vision, & dry eyes

Front 7

Therapeutic uses of Muscarinic Agonists

Back 7

Urinary retention & GI uses

Front 8

Other muscarinic agonists:

Back 8

Cevimeline
Pilocarpine (Gluacoma)
Acetylcholine (Miosis)
Muscarine (present in poisonous mushrooms)

Front 9

What is the best known muscarinic antagonist?

Back 9

Atropine - found in nature

MOA- no direct effect of its own, muscarinic receptor blockade

Front 10

What are the therapeutic uses of atropine?

Back 10

-preanesthetic med
-disorders of the eye
-bradycardia
-intestinal hypertonicity and hypermotility
-muscarinic agonist poisioning
-peptic ulcer disease
-asthma
-biliary colic

Front 11

What are the adverse effects of Atropine?

Back 11

-Xerostomia (dry mouth)
-blurred vision and photophobia
-elevation of intraocular pressure
- urinary retention
-constipation
-anhidrosis (failure of the sweat glands)
-tachycardia
-asthma

Front 12

Drug interactions of atropine?

Back 12

-avoid combining with other drugs capable of causing muscarinic blockades

Front 13

Specific drugs used for Over Active Bladder

Back 13

Oxybutynin (Ditropan, Oxytrol, Gelnique)
--could be a syrup, extended-release tabs, or transdermal patch and gel

Darifenacin
Solifenacin
Tolterodine
Trospium
Fesoterodine

Front 14

Other muscarinic Antagonists

Back 14

Scopolamine
Ipratropium bromide
Antisecretory anticholinergics
Dicyclomine
Pirenzepine and Telenzepine
Mydriatic-cycloplegics
Centrally acting anticholinergics

Front 15

When is Bethanechol (Muscinaric Agonist) contraindicated for patients?

Back 15

-peptic ulcer disease, Urinary tract obstruction, intestinal obstruction, coronary insufficiency, hypotension, asthma, and hyperthyroidism

Front 16

How do you evaluate the therapuetic effects of Bethanechol (Muscarinic Agonist)?

How do you minimize adverse effects?

Back 16

Monitor I&O to evaluate treatment of urinary retention


Monitor BP and pulse. Teach patients s/s of muscarinic excess and advise them to notify the prescriber if they occur

Front 17

When is Atropine (Muscarinic Antagonist) contraindicated for patients?

Back 17

Glaucoma, intestinal atony, urinary tract obstruction, and tachycardia

Use with caution in patients with asthma

Front 18

How would you minimize adverse effects of a muscarinic antagonist?

Back 18

-- teach patients that xerostomia (dry mouth) can be relieved by sipping fluids, chewing sugar free gum, treating the mouth with a saliva substitute (salivart), and using an alcohol free mouth wash.
-- warn patients to avoid hazardous activities if vision is impaired
-- advise patients to wear sunglasses outdoors
-- advise patients that urinary retention can be minimized by voiding just prior to taking anticholinergic meds
-- advise patients that constipation can be reduced by increasing dietary fiber and fluids and treated with a laxative if severe
-- advise patients to avoid vigorous exercise in warm environments

Front 19

Do not mix muscarinic drugs with?

Back 19

antihistamines
tricyclic antidepressants
phenothiazines

Front 20

Why does Bethanechol (Urecholine) relieve urinary retention?

Back 20

It relaxes the trigone and sphinctre muscles and increases voiding pressure by contracting the detrusor muscle causing an urge to go

Front 21

What adverse effects are associated with Bethanechol (Urecholine)?

Back 21

-Hypotension
-Bradycardia
(CONTRAINDICATED FOR PATIENTS WITH LOW BP and/or LOW CARDIAC OUTPUT)
-Excessive salivation, increased secretion of gastric acid, abdominal cramps, and diarrhea
(CONTRAINDICATED IN PATIENTS WITH GASTRIC ULCERS because stimulation of acid secretion could intensify gastric erosion causing bleeding and possibly perforation, CONTRAINDICATED FOR PATIENTS WITH INTESTINAL OBSTRUCTION AND SURGERY OF THE BOWEL- increased motility and tone could cause rupture in bowel wall)
-Increases pressure within the urinary tract (can be hazardous for patients with UT obstructions or weakness of the bladder wall)
-Exacerbation of asthma by causing bronchoconstriction
-Dysrhythmias in hyperthyroid patients

Front 22

What is the source of muscarinic posioning?

Symptoms?

Treatment?

Back 22

-- Direct-acting muscarinic agonists and Cholinesterase inhibitors

-- result from excessive activation of muscarinic receptors : dry mouth, blurred vision, photophobia, hyperthermia, hallucinations, delirium, and hot dry flushed skin.

-- muscarinic blocking agent such as atropine, charchoal, physostigmine- inhibitor of acetylcholinesterase

Front 23

When should patients take Bethanechol?

Back 23

1 hour before meals or 2 hours after to reduce gastric upset

Front 24

Other nursing considerations for Bethanechol

Back 24

-Make sure a bedpan or bathroom is readily accessible due to rapid and dramatic results
-monitor fluid intake and output to evaluate treatment of urinary retention

Front 25

What should patients do when taking Cevimeline (muscarinic agonist)

Back 25

Increase fluid intake

Front 26

What is used for sjorgens dry eye?

Back 26

Pilocarpine and cevimeline (Muscarinic agonists) increases secretions

Front 27

Atropine's pharmacologic effects

Back 27

-Increases heart rate
-Decreases secretions
-Relaxes bronchi
-Decreases tone of the urinary bladder detrusor
-Decreases tone and motility of the GI tract
-Dilates the pupil
-Relaxes ciliary muscles (focuses on far vision)
- CNS excitation
-Toxic doses might cause hallucinations and delirium
-Extremely high doses can result in coma, respiratory arrest and death

Front 28

How is Atropine used as a preanesthetic medication

Back 28

-Blocks secretions that could clog respiratory tract and stops the heart from EXTREME bradycardia

Front 29

How is atropine used in disorders of they eye?

Back 29

can dilate the pupil and relax ciliary muscle which can help during eye exams and ocular surgery

Front 30

How is atropine used in bradycardia?

Back 30

Can accelerate heart rate in certain patients with bradycardia

Front 31

How is Atropine used in intestinal hypertonicity and hypermotility?

Back 31

-Decreases both the tone and motility of intestinal smooth muscle
this can be beneficial in conditions such as diverticulitis
-reduces the frequency of bowel movements and abdominal cramps

Front 32

How is Atropine used with muscarinic agonist poisoning?

Back 32

- It blocks the muscarinic receptors and reverses all signs of muscarinic poisoning

Front 33

What other therapeutic uses does Atropine have?

Back 33

Peptic ulcer disease (stops secretion of gastric acid)

Asthma (promotes bronchial dilation)

Biliary Colic (relax biliary tract helping to alleviate discomfort)

HOWEVER THESE ARE NOT RECOMMENDED AS HIGHLY DUE TO OTHER COMPLICATIONS WITH USING IT

Front 34

What are the adverse effects of Atropine?

Back 34

-Xerostomia (Dry mouth)
-Blurred vision and Photophobia
-Elevation of intraocular pressure due to paralysis of the iris sphincter
-Urinary Retention
-Constipation
-Anhidrosis (absence of sweat)
-Tachycardia
-Asthma problems by thickening and drying the bronchial secretions causing bronchial plugging

Front 35

Atropine Drug interactions

Back 35

-Antihistamines
-Phenothiazine antipsychotics
-Tricyclic antidepressants
-----all enhance the antimuscarinic effects of atropine

Front 36

Adverse effect nursing management for Atropine: Xerostomia

Back 36

-Teach the patient dry mouth can be alleviated by sipping fluids, chewing sugar free gum, treating the mouth with a saliva substitute and using acohol free mouthwash
-patient should avoid sugary gum, hard candy, and cough drops due to increase in tooth decay

Front 37

Adverse effect nursing management for Atropine: Blurred vision
Photophobia

Back 37

- Patients should be forewarned about the possibility of blurred vision and should be advised to avoid hazardous activities (driving) if vision is impaired
-Patient should be advised to wear dark glasses if photophobia is a problem. Hospital room should be dark

Front 38

Adverse effect nursing management for Atropine: Elevation of Intraocular pressure

Back 38

-Do not use with patients with glaucoma or who have a predisposition to glaucoma (people older than 40)

Front 39

Adverse effect nursing management for Atropine: Urinary Retention

Back 39

-In the event of severe urinary retention cathetarization or treatment with a muscarinic agonist (Bethanechol) may be required
-Patients should void PRIOR to taking medication

Front 40

Adverse effect nursing management for Atropine: Constipation

Back 40

-Increase fiber, fluids and physical activity
-May need a laxative
Contraindicated for patients with intenstinal atony- INTESTINAL TONE IS ALREADY LOW

Front 41

Adverse effect nursing management for Atropine: Anhidrosis

Back 41

-Increased risk for hyperthermia
-Patients should avoid activity that might lead to overheating

Front 42

Adverse effect nursing management for Atropine:
Tachycardia:

Back 42

-Use with caution in patients with pre existing tachycardia

Front 43

What anticholinergic drugs are used for overactive bladder?

What do they do?

Back 43

Oxybutynin
Tolterodine

--block muscarinic receptors and inhibit bladder contractions and the urge to void

Front 44

What side effects do the overactive bladder drugs have?

Back 44

- dry mouth -Primary concern
- constipation, urinary retention, blurred vision, photophobia, tachycardia
-cognitive impairment in the elderly

Front 45

How do you reduce anticholinergic side effects?

Back 45

- Using long-acting formulations
-----provide a steady but low level of the drug
- Using drugs that do not cross the blood-brain barrier
-----unable to cause CNS effects
- Using drugs that are selevtive for muscarinic receptors in the bladder
-----will have less side effects

Front 46

Oxybutynin comes in what routes?

Back 46

Syrup
Extended-release tablet
Transdermal patch
Topical Gel