1. Drugs Affecting the Autonomic Nervous System
Cholinergic Agents and Cholinergic Blocking Agents

2. Cholinergic Agents
Drugs that stimulate the parasympathetic nervous system (PSNS)
The PSNS is the opposing system to the SNS

3. Cholinergic Agents Also known as cholinergic agonists or
parasympathomimetics

4. Instructors may wish to use EIC Image #56: The Parasympathetic and Sympathetic Nervous Systems and Their Relationships to One Another

5. Cholinergic Agents Mimic the effects of the PSNS neurotransmitter
Acetylcholine (ACh)

6. Cholinergic Receptors
Two types, determined by:
Location
Action once stimulated
Nicotinic receptors and Muscarinic receptors

7. Nicotinic Receptors Located in the ganglia of both the PSNS and SNS
Named “nicotinic” because can be stimulated by the alkaloid nicotine

8. Muscarinic Receptors Located postsynaptically:
Smooth muscle
Cardiac muscle
Glands of parasympathetic fibers
Effector organs of cholinergic sympathetic fibers
Named “muscarinic” because can be stimulated by the alkaloid muscarine

9. Instructors may wish to insert EIC Image #57: The Sympathetic, Parasympathetic, and Somatic Nervous Systems
This slide illustrates location of the nicotinic and muscarinic receptors within the PSNS.

10. Adrenergic Agents: Mechanism of Action
Lisa L. Hernandez:
Is there copy missing at the end? Inhibiting what?
HHS:
HHS:
Adrenergic Agents: Mechanism of Action
Direct-acting (agonist)
Bind to cholinergic receptors, causing stimulation

11. Adrenergic Agents: Mechanism of Action
Indirect-acting
Inhibit the enzyme “cholinesterase”
Result: more ACh is available at the receptors

12. Indirect-Acting Cholinergic Agents (Cholinesterase Inhibitors)
Reversible
Bind to cholinesterase for a period of minutes to hours
Irreversible
Bind to cholinesterase and form a permanent covalent bond
The body must make new cholinesterase

13. Drug Effects of Cholinergic Agents
Effects seen when the PSNS is stimulated.
The PSNS is the “rest and digest” system.

14. Drug Effects of Cholinergic Agents
“SLUDGE”
Salivation
Lacrimation
Urinary incontinence
Diarrhea
Gastrointestinal cramps
Emesis

15. Drug Effects of Cholinergic Agents
Stimulate intestine and bladder
Increased gastric secretions
Increased gastrointestinal motility
Increased urinary frequency
Stimulate pupil
Constriction (miosis)
Reduced intraocular pressure
Increased salivation and sweating

16. Drug Effects of Cholinergic Agents
Cardiovascular effects
Decreased heart rate
Vasodilation
Respiratory effects
Bronchial constriction, narrowed airways

17. Drug Effects of Cholinergic Agents
At recommended doses, the cholinergics primarily affect the MUSCARINIC receptors.
At high doses, cholinergics stimulate the NICOTINIC receptors.

18. Drug Effects of Cholinergic Agents
DESIRED EFFECTS: from muscarinic receptor stimulation
Many undesirable effects are due to stimulation of the nicotinic receptors

19. Cholinergic Agents: Therapeutic Uses
Direct-Acting Agents
Reduce intraocular pressure
Useful for glaucoma and intraocular surgery
Examples: acetylcholine, carbachol, pilocarpine
Topical application due to poor oral absorption

20. Cholinergic Agents: Therapeutic Uses
Direct-Acting Agent—bethanechol
Increases tone and motility of bladder and 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 SC injection

21. Cholinergic Agents: Therapeutic Uses
Indirect-Acting Agents
Cause skeletal muscle contractions
Used for diagnosis and treatment of myasthenia gravis
Used to reverse neuromuscular blocking agents
Used to reverse anticholinergic poisoning (antidote)
Examples: physostigmine, pyridostigmine

22. Cholinergic Agents: Therapeutic Uses
Indirect-Acting Agent—donepezil (Aricept)
Used in the treatment of mild to moderate Alzheimer’s disease.
Helps to increase or maintain memory and learning capabilities.

23. Cholinergic Agents: Side Effects
Side effects are a result of overstimulation of the PSNS.
Cardiovascular:
Bradycardia, hypotension, conduction abnormalities (AV block and cardiac arrest)
CNS:
Headache, dizziness, convulsions
Gastrointestinal:
Abdominal cramps, increased secretions, nausea, vomiting

24. Cholinergic Agents: Side Effects
Side effects are a result of overstimulation of the PSNS.
Respiratory:
Increased bronchial secretions, bronchospasms
Other:
Lacrimation, sweating, salivation, loss of binocular accommodation, miosis

25. Cholinergic Agents: Interactions
Anticholinergics, antihistamines, sympathomimetics
Antagonize cholinergic agents, resulting in decreased responses

26. Cholinergic Agents: Nursing Implications
Keep in mind that these agents will stimulate the PSNS and mimic the action of ACh.
Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, or coronary artery disease.
Perform baseline assessment of VS and systems overview.

27. Cholinergic Agents: Nursing Implications
Medications should be taken as ordered and not abruptly stopped.
The doses should be spread evenly apart to optimize the effects of the medication.
Overdosing can cause life-threatening problems. Patients should not adjust the dosages unless directed by the physician.

28. Cholinergic Agents: Nursing Implications
Encourage patients with myasthenia gravis to take medication 30 minutes before eating to help improve chewing and swallowing.
When donepezil is prescribed for Alzheimer’s disease, be honest with caregivers and patients that the drug is for management of symptoms, not for a cure.
Therapeutic effects of donepezil may not occur for up to 6 weeks.

29. Cholinergic Agents: Nursing Implications
Atropine is the antidote for cholinergics. It should be available in the patient’s room for immediate use if needed.
Patients should notify their physician if they experience muscle weakness, abdominal cramps, diarrhea, or difficulty breathing.

30. Cholinergic Agents: Nursing Implications
Monitor for side effects, including:
Increased respiratory Abdominal cramping secretions
Bronchospasms Dysrhythmias
Difficulty breathing Hypotension
Nausea and vomiting Bradycardia
Diarrhea Increased sweating
Increase in frequency and urgency of voiding patterns

31. Cholinergic Agents: Nursing Implications
Monitor for therapeutic effects:
Alleviated signs and symptoms of myasthenia gravis
In postoperative patients with decreased GI peristalsis, look for:
Increased bowel sounds
Passage of flatus
Occurrence of bowel movements
In patients with urinary retention/hypotonic bladder, urination should occur within 60 minutes of bethanecol administration

32. Cholinergic Blocking Agents
Drugs that block or inhibit the actions of acetylcholine (ACh) in the parasympathetic nervous system (PSNS)

33. Cholinergic Blocking Agents: Mechanism of Action
Competitive antagonists
Compete with ACh
Block ACh at the muscarinic receptors in the PSNS
As a result, ACh is unable to bind to the receptor site and cause a cholinergic effect.

34. Cholinergic Blocking Agents: Mechanism of Action
Once these drugs bind to receptors, they inhibit nerve transmission at these receptors.

35. Instructors may wish to use EIC Image #58: Site of Action of Cholinergic Blockers Within the PSNS

36. Cholinergic Blocking Agents: Chemical Class
Natural Synthetic/Semisynthetic
atropine anisotropine clidinium
belladonna dicyclomine glycopyrrolate
hyoscyamine hexocyclium homatropine
scopolamine ipratropium isopropamide
oxybutynin propantheline
tolterodine tridihexethyl

37. Drug Effects of Cholinergic Blocking Agents
Cardiovascular
Small doses: decrease heart rate
Large doses: increase heart rate
CNS
Small doses: decrease muscle rigidity and tremors
Large doses: drowsiness, disorientation, hallucinations

38. Drug Effects of Cholinergic Blocking Agents
Eye
Dilated pupils (mydriasis)
Decreased accommodation due to paralysis of ciliary muscles (cycloplegia)
Gastrointestinal
Relax smooth muscle tone of GI tract
Decrease intestinal and gastric secretions
Decrease motility and peristalsis

39. Drug Effects of Cholinergic Blocking Agents
Genitourinary
Relaxed detrusor muscle
Increased constriction of internal sphincter
Result: urinary retention
Glandular
Decreased bronchial secretions, salivation, sweating
Respiratory
Decreased bronchial secretions
Dilated bronchial airways

40. Cholinergic Blocking Agents: Therapeutic Uses
CNS
Decreased muscle rigidity and muscle tremors
Parkinson’s disease
Drug-induced extrapyramidal reactions

41. Cholinergic Blocking Agents: Therapeutic Uses
Cardiovascular
Affect the heart’s conduction system
Low doses: slow the heart rate
High doses: block inhibitory vagal effects on the SA and AV node pacemaker cells
Result: increased heart rate

42. Cholinergic Blocking Agents: Therapeutic Uses
Atropine
Used primarily for cardiovascular disorders
Sinus node dysfunction
Symptomatic second-degree heart block
Sinus bradycardia with hemodynamic compromise (advanced life support)

43. Cholinergic Blocking Agents: Therapeutic Uses
Respiratory
Blocking the cholinergic stimulation of the PSNS allows unopposed action of the SNS.
Results:
Decreased secretions from nose, mouth, pharynx, bronchi
Relaxed smooth muscles in bronchi and bronchioles
Decreased airway resistance
Bronchodilation

44. Cholinergic Blocking Agents: Therapeutic Uses
Respiratory agents are used to treat:
Exercise-induced bronchospasms
Chronic bronchitis
Asthma
Chronic obstructive pulmonary disease

45. Cholinergic Blocking Agents: Therapeutic Uses
Gastrointestinal
PSNS controls gastric secretions and smooth muscles that produce gastric motility.
Blockade of PSNS results in:
Decreased secretions
Relaxation of smooth muscle
Decreased GI motility and peristalsis

46. Cholinergic Blocking Agents: Therapeutic Uses
Gastrointestinal agents are used to treat:
Peptic ulcer disease
Irritable bowel disease
GI hypersecretory states

47. Cholinergic Blocking Agents: Therapeutic Uses
Genitourinary
Relaxed detrusor muscles of the bladder
Increased constriction of the internal sphincter
Reflex neurogenic bladder
Incontinence

48. Cholinergic Blocking Agents: Side Effects
Body System Side/Adverse Effects
Cardiovascular Increased heart rate, dysrhythmias
CNS CNS excitation, restlessness, irritability, disorientation, hallucinations, delirium

49. Cholinergic Blocking Agents: Side Effects
Body System Side/Adverse Effects
Eye Dilated pupils, decreased visual accommodation, increased intraocular pressure
Gastrointestinal Decreased salivation, decreased gastric secretions, decreased motility

50. Cholinergic Blocking Agents: Side Effects
Body System Side/Adverse Effects
Genitourinary Urinary retention
Glandular Decreased sweating
Respiratory Decreased bronchial secretions

51. Cholinergic Blocking Agents: Interactions
Antihistamines, phenothiazines, tricyclic antidepressants, MAOIs
When given with cholinergic blocking agents, cause ADDITIVE cholinergic effects, resulting in increased effects

52. Cholinergic Blocking Agents: Nursing Implications
Keep in mind that these agents will block the action of ACh in the PSNS.
Assess for allergies, presence of BPH, glaucoma, tachycardia, MI, CHF, hiatal hernia, and GI or GU obstruction.
Perform baseline assessment of VS and systems overview.

53. Cholinergic Blocking Agents: Nursing Implications
Medications should be taken exactly as prescribed to have the maximum therapeutic effect.
Overdosing can cause life-threatening problems.
Blurred vision may cause problems with driving or operating machinery.
Patients may experience sensitivity to light and may want to wear dark glasses or sunglasses.

54. Cholinergic Blocking Agents: Nursing Implications
When giving ophthalmic solutions, apply pressure to the inner canthus to prevent systemic absorption.
Dry mouth may occur; can be handled by chewing gum, frequent mouth care, and hard candy.
Check with physician before taking any other medication, including OTC medications.
ANTIDOTE for atropine is physostigmine salicylate (Antilirium).

55. Cholinergic Blocking Agents: Nursing Implications
Anticholinergics may lead to higher risk for heat stroke due to effects on heat-regulating mechanisms.
Teach patients to limit physical exertion, and avoid high temperatures and strenuous exercise.
Emphasize the importance of adequate fluid and salt intake.

56. Cholinergic Blocking Agents: Nursing Implications
Patients should report the following to their physician: urinary hesitancy and/or retention, constipation, palpitations, tremors, confusion, sedation or amnesia, excessive dry mouth (especially if they have chronic lung infections or disease), or fever

57. Cholinergic Agents: Nursing Implications
Monitor for therapeutic effects:
For patients with Parkinson’s disease: fewer tremors and decreased salivation and drooling
For patients with peptic ulcer disease: decreased abdominal pain

58. Cholinergic Blocking Agents: Nursing Implications
Monitor for side effects, including:
Constipation Tachycardia
Tremors Confusion
Hallucinations Sedation
Urinary retention Hot, dry skin
Fever
CNS depression (occurs with large doses of atropine)