1. Drugs Affecting Autonomic Nervous System 2

2. Cholinergic Agents
Drugs that stimulate the parasympathetic nervous system (PSNS)
The PSNS is the opposing system to the SNS Also known as cholinergic agonists
or parasympathomimetics
Mimic the effects of the PSNS neurotransmitter Acetylcholine (ACh)

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

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

5. 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

6. Parasypathomimetic drugs
Have effect similar to those produced by activating by PSNS.
Examples:
Acetylcholine
Carbachol
Bethanechol
Pilocarpine

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

8. 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

9. 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

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

11. Drug Effects of Cholinergic Agents
At recommended doses, the cholinergics primarily affect the MUSCARINIC receptors.
At high doses, cholinergics stimulate the NICOTINIC receptors.
DESIRED EFFECTS: from muscarinic receptor stimulation
Many undesirable effects are due to stimulation of the nicotinic receptors

12. 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

13. 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

14. Acetylcholine: is essential for all voluntary movement, it is action very short lived it is quickly broken down to choline by cholinesterase and acetate so it not used therapeutically.

15. Carbachol
Is a synthetic substance related to acetylcholine it is not broken down by cholinesterase and it is action are there fore much more prolonged may be given by SC or orally.
Uses to treat uriary retention following surgical operation, no mechnical obstruction.
Side effect: diarrehea, colic, marked fall in blood pressure
Same as Bethanechol

16. Pilocarpine: is used only as eye drops where it causes constriction of the pupil.

17. 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

18. Side effects Respiratory:
Increased bronchial secretions, bronchospasms
Other:
Lacrimation, sweating, salivation

19. 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.

20. 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.

21. 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.

22. 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.

23. 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

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

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

26. 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

27. 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

28. 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

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

30. 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

31. 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)

32. 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

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

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

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

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

37. 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

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

39. 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.

40. 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.

41. 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).

42. 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.

43. 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