Cholinergic Drugs

Question 1

Cholinergic Drugs action

also known as

Answer 1

Drugs that stimulate the parasympathetic nervous system (the opposing system to the sympathetic nervous system)

Also known as cholinergic agonists or parasympathomimetics

Mimic effects of the parasympathetic nervous system neurotransmitter acetylcholine (ACh)

Question 2

Cholinergic Receptors

Answer 2

Two types, determined by:
-Location
-Action once stimulated

Nicotinic receptors
Muscarinic receptors

Question 3

Nicotinic Receptors

location

Answer 3

Located in the ganglia of both systems

Named nicotinic because they can be stimulated by the alkaloid nicotine.

Question 4

Muscarinic Receptors

location

Answer 4

Located postsynaptically in the effector organs of the parasympathetic system
-Smooth muscle
-Cardiac muscle
-Glands

Named muscarinic because they can be stimulated by the alkaloid muscarine.

Question 5

Direct-acting cholinergic agonists

Answer 5

Bind to cholinergic receptors, activating them

Question 6

Indirect-acting cholinergic agonists

also known as

action

Answer 6

Also known as cholinesterase inhibitors

Inhibit the enzyme acetylcholinesterase, which breaks down ACh

Results in more ACh available at the receptors

Question 7

Indirect-Acting (Cholinesterase Inhibitors)

2 types

Differences between the two

Answer 7

Reversible
-Bind to cholinesterase for a short period of time

Irreversible
-Bind to cholinesterase for a long period of time
-Bind to cholinesterase and form a permanent covalent bond
-The body must make new cholinesterase to break these bonds.

Question 8

Cholinergic Drug Effects

Answer 8

Effects seen when parasympathetic system is stimulated

This system is the “rest and digest” system.

Question 9

Cholinergic drug 5 effects on body?

Answer 9

Stimulate intestine and bladder
-Increased gastric secretions
-Increased gastrointestinal motility
-Increased urinary frequency

Stimulate pupils
-Constriction (miosis)
-Reduced intraocular pressure

Increased salivation and sweating

Cardiovascular effects
-Decreased heart rate
-Vasodilation

Respiratory effects
-Bronchial constriction, narrowed airways

Question 10

At recommended doses, cholinergics primarily affect _____ receptors.

At high doses, cholinergics stimulate ______ receptors.

Desired effects are from _____ receptor stimulation.

Many undesirable effects are caused by stimulation of ________ receptors.

Answer 10

At recommended doses, cholinergics primarily affect muscarinic receptors.

At high doses, cholinergics stimulate nicotinic receptors.

Desired effects are from muscarinic receptor stimulation.

Many undesirable effects are caused by stimulation of nicotinic receptors.

Question 11

Direct-acting drugs indication

Answer 11

Reduce intraocular pressure

Useful for glaucoma and intraocular surgery
-carbachol
-pilocarpine

-Topical application because of poor oral absorption

Question 12

pilocarpine

Answer 12

Useful for glaucoma and intraocular surgery

Question 13

bethanechol

Answer 13

Direct-acting drug

Increases tone and motility of bladder and gastrointestinal (GI) tract

Relaxes sphincters in bladder and GI tract, allowing them to empty

Helpful for postsurgical atony of the bladder and GI tract

Oral dose or subcutaneous injection

Question 14

succinylcholine

Answer 14

Direct-acting drug: succinylcholine

Used as a neuromuscular blocker in general anaesthesia

Intravenous

Question 15

Indirect-acting drugs indications

Answer 15

Increase ACh concentrations at the receptor sites, which leads to stimulation of the effector cells

Cause skeletal muscle contractions

Used for diagnosis and treatment of myasthenia gravis

Used to reverse neuromuscular blocking drugs

Used to reverse anticholinergic poisoning (antidote)
-Example: physostigmine

Question 16

physostigmine

Answer 16

Indirect acting

Used to reverse anticholinergic poisoning (antidote)

Question 17

donepezil (Aricept®)

Answer 17

Indirect-acting anticholinesterase drugs

Used for treatment of mild to moderate Alzheimer’s disease

Question 18

Cholinergic drugs Contraindications

Answer 18

Known drug allergy
GI or genitourinary (GU) tract obstruction
Bradycardia
Defects in cardiac impulse conduction
Hyperthyroidism
Epilepsy
Hypotension
Chronic obstructive pulmonary disease
Parkinson’s disease

Question 19

Cholinergic drugs AEs

Answer 19

Adverse effects are a result of overstimulation of the parasympathetic system.

Cardiovascular
Bradycardia, hypotension, syncope, conduction abnormalities (atrioventricular block and cardiac arrest)

Central nervous system
Headache, dizziness, convulsions, ataxia

Gastrointestinal
Abdominal cramps, increased secretions, nausea, vomiting, diarrhea, weight loss

Respiratory
Increased bronchial secretions, bronchospasms

Other
Lacrimation, sweating, salivation, miosis

Question 20

Cholinergic Crisis

Answer 20

Circulatory collapse, hypotension, bloody diarrhea, shock, and cardiac arrest.

SLUDGE (salivation, lacrimation, urinary incontinence, diarrhea, gastrointestinal cramps, and emesis)

Early signs
Abdominal cramps, salivation, flushing of the skin, nausea and vomiting, transient syncope, transient complete heart block, dyspnea, and orthostatic hypotension

Question 21

Cholinergic Crisis treatment

Answer 21

Treatment in early phase: atropine sulphate, a cholinergic antagonist

Treatment of severe cardiovascular reactions or bronchoconstriction: epinephrine, an adrenergic agonist

Question 22

Cholinergic drugs interactions

Answer 22

Anticholinergics, antihistamines, sympathomimetics; Antagonize cholinergic drugs, resulting in decreased responses

Other cholinergic drugs; Additive effects

Question 23

bethanechol (Duvoid®)

direct or indirect?

indicated for?

AEs

Interaction

Answer 23

Direct-acting cholinergic agonist

Uses
-Treatment of acute postoperative and postpartum nonobstructive urinary retention
-Management of urinary retention associated with neurogenic atony of the bladder

Contraindications
Known drug allergy, hyperthyroidism, peptic ulcer, active bronchial asthma, cardiac disease or coronary artery disease, epilepsy, and parkinsonism

Adverse effects: syncope, hypotension with reflex tachycardia, headache, seizure, GI upset, and asthmatic attacks

Interactions: acetylcholinesterase inhibitors (i.e., indirect-acting cholinergics)

Question 24

donepezil (Aricept)

action

indicated for?

AEs

Intercations

Answer 24

Cholinesterase inhibitor that works centrally in the brain to increase levels of ACh by inhibiting acetylcholinesterase

Used in the treatment of mild to moderate Alzheimer’s disease

Similar cholinesterase inhibitors include galantamine and rivastigmine.

Contraindications: known drug allergy

Adverse effects: GI upset (including ulcer risk caused by increased gastric secretions), drowsiness, dizziness, insomnia, and muscle cramps.

The effects on the cardiovascular system are complex and may include bradycardia, syncope, hypotension with reflex tachycardia, or hypertension.

Interacting drugs: anticholinergics (counteract donepezil effects) and nonsteroidal anti-inflammatory drugs (NSAIDs)

Question 25

pyridostigmine (Mestinon®)

direct or indirect?

action?

indicated for?

Answer 25

Indirect-acting cholinergic drugs that work to increase ACh by inhibiting acetylcholinesterase

Use: myasthenia gravis

Question 26

Edrophonium (Tensilon):

direct or indirect?

indicated for? Two

Answer 26

indirect-acting cholinergic drug that is used to diagnose myasthenia gravis.

It can also be used to differentiate between myasthenia gravis and cholinergic crisis.

Question 27

pyridostigmine and physostigmine

Answer 27

Uses: reversing the effects of nondepolarizing neuromuscular blocking drugs;

treating severe overdoses of tricyclic antidepressants; and

antidote after toxic exposure to nondrug anticholinergic agents, including those used in chemical warfare

Question 28

Ginkgo

common uses (three)

Answer 28

Common uses
-Prevent memory loss
-Vertigo
-Tinnitus

May cause GI upset, headache, bleeding

Potential interactions
-Aspirin
-NSAIDs
-Anticoagulants
-Anticonvulsants

Question 29

Nursing Implications

Answer 29

Note that these drugs will stimulate the parasympathetic nervous system and mimic the action of ACh.

Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, and coronary artery disease.

Perform baseline assessment of vital signs and systems overview.

Medications should be taken as ordered and not abruptly stopped.

Doses should be spread evenly apart to optimize the effects of the medication.

Overdosing can cause life-threatening problems. Patients should not adjust dosages unless directed by their health care provider.

To help improve chewing and swallowing, encourage patients with myasthenia gravis to take medication 30 minutes before eating.

When cholinergic drugs are prescribed for Alzheimer’s disease, be honest with caregivers and patients and tell them that the drugs are for the management of symptoms, not a cure.

Therapeutic effects of anti-Alzheimer’s drugs may not occur for up to 6 weeks.

Patients should notify their physicians if they experience muscle weakness, abdominal cramps, diarrhea, or difficulty breathing.

Question 30

Atropine

Answer 30

is the antidote for cholinergics, and it should be available in the patient’s room for immediate use if needed.

Question 31

Monitor for therapeutic effects

Answer 31

Alleviated signs and symptoms of myasthenia gravis

In postoperative patients with decreased GI peristalsis, monitor for:
-Increased bowel sounds
-Passage of flatus
-Occurrence of bowel movements

Monitor for therapeutic effects.
-In patients with urinary retention or hypotonic bladder, urination should occur within 60 minutes of bethanechol administration.
-In patients with Alzheimer’s disease:
–Improvement in symptoms
–Improvement in mood and decrease in confusion