ANS pharmacology lectures

1. DRUGS AFFECTING THE
AUTONOMIC NERVOUS SYSTEM
Cholinergic Drugs

2. Cholinergic Drugs
 Describe the cholinergic drug effects on major
body systems.
 Discuss the nursing process related to the care
of patients receiving cholinergic drugs for select
problems.

3. Cholinergic Drugs
 Drugs that stimulate the
parasympathetic nervous system (PSNS)
 opposing system to the SNS
 Known as: cholinergic agonists or parasympathomimetics
 Mimic the effects of the PSNS neurotransmitter:
acetylcholine (Ach)
 Two types of Receptors:
 determined by: Location & Action once stimulated
 Muscarinic receptors – recommended doses with desired effect
 Nicotinic receptors – higher doses with undesirable effects

5. Cholinergic Drugs
Mechanism of Action
 Direct-acting cholinergic agonists
 Bind to cholinergic receptors, activating them
 Indirect-acting cholinergic agonists
 Inhibit the enzyme acetylcholinesterase - preventing,
which breaks down ACh - moreACh is available at the
receptors
 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 to break these
bonds

6. Cholinergic Drugs
“rest and digest” system
“SLUDGE”
 Salivation
 Lacrimation
 Urinary incontinence
 Diarrhea
 Gastrointestinal cramps
 Emesis

7. Cholinergic Drugs
Drug Effects
 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

8. Cholinergic Drugs
Drugs
 Bethanechol (Urecholine) – urinary retention
 Cevimeline (Evoxac) – Xerostomia
 Memantine (Namenda) – Alzheimer’s dementia
 Physostigmine (Antilirium) – reversal of
anticholinergic drugs effects
 Pyridostigmine (Mestinon) – Myasthenia gravis

9. Cholinergic Drugs
Indications
Direct-acting drugs
 Reduce intraocular pressure
 Topical useful for glaucoma and intraocular surgery
 pilocarpine

10. Cholinergic Drugs
Indications
Direct-acting drug—bethanechol (Urecholine)
 Increases tone and motility of bladder and GI tract
 Relaxes sphincters in bladder and GI tract, allowing
them to empty
 Used to reverse postsurgical atony of the bladder
and GI tract
 Oral dose or SC injection

11. Cholinergic Drugs
Indications
Indirect-acting drugs
 Cause skeletal muscle contractions
 Used for diagnosis and treatment of myasthenia gravis
 Pyridostigmine (Mestinon) – Myasthenia gravis
 Used to reverse neuromuscular blocking drugs/anesthesia
 Used to reverse anticholinergic poisoning (antidote)
 Examples: physostigmine (Antilirium)

12. Cholinergic Drugs
Indications
Indirect-acting drugs—cevimeline (Evoxac)
 Used to treat xerostomia (dry mouth)
resulting from Sjögren’s syndrome

13. Cholinergic Drugs
Adverse Effects
Adverse 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
 Respiratory
 Increased bronchial secretions, bronchospasm
 Other
 Lacrimation, sweating, salivation, loss of binocular accommodation,
miosis

14. Cholinergic Drugs
Interactions
 Anticholinergics, antihistamines,
sympathomimetics
 Antagonize cholinergic drugs, resulting in
decreased responses
 Other cholinergic drugs
 Additive effects

15. Cholinergic Drugs
Nursing Implications
 Assess for allergies, presence of GI or GU obstructions, asthma, peptic
ulcer disease, or coronary artery disease
 Perform baseline assessment of vital signs and systems overview
 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. Only physicians
should adjust the dosages

16. Cholinergic Drugs
Nursing Implications
 Encourage patients with myasthenia gravis to take
medication 30 minutes before eating to help improve
chewing and swallowing
 When cholinergic drugs are prescribed for Alzheimer’s
disease, be honest with caregivers and patients that the
drugs are for management of symptoms, not a cure
 Therapeutic effects of anti-Alzheimer’s drugs may not
occur for up to 6 weeks

17. Cholinergic Drugs
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
bethanechol administration
 ALSO monitor for adverse effects