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  • 1. Cholinergic Agents and Cholinergic Blocking Agents
  • 2.
    • Drugs that stimulate the parasympathetic nervous system (PSNS)
    • The PSNS is the opposing system to the SNS
  • 3.
    • Also known as
    • cholinergic agonists
    • or
    • parasympathomimetics
  • 4.  
  • 5.
    • Mimic the effects of the PSNS neurotransmitter
    • Acetylcholine (ACh)
  • 6.
    • Two types, determined by:
    • Location
    • Action once stimulated
    • Nicotinic receptors and Muscarinic receptors
  • 7.
    • Located in the ganglia of both the PSNS and SNS
    • Named “nicotinic” because can be stimulated by the alkaloid nicotine
  • 8.
    • 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.
    • This slide illustrates location of the nicotinic and muscarinic receptors within the PSNS.
  • 10.
    • Direct-acting (agonist)
      • Bind to cholinergic receptors, causing stimulation
    Lisa L. Hernandez: Is there copy missing at the end? Inhibiting what? HHS: HHS:
  • 11.
    • Indirect-acting
      • Inhibit the enzyme “cholinesterase”
      • Result: more ACh is available at the receptors
  • 12.
    • 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.
    • Effects seen when the PSNS is stimulated.
    • The PSNS is the “rest and digest” system.
  • 14.
    • “ SLUDGE”
    • S alivation
    • L acrimation
    • U rinary incontinence
    • D iarrhea
    • G astrointestinal cramps
    • E mesis
  • 15.
    • 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.
    • Cardiovascular effects
      • Decreased heart rate
      • Vasodilation
    • Respiratory effects
      • Bronchial constriction, narrowed airways
  • 17.
    • At recommended doses, the cholinergics primarily affect the MUSCARINIC receptors.
    • At high doses, cholinergics stimulate the NICOTINIC receptors.
  • 18.
    • DESIRED EFFECTS: from muscarinic receptor stimulation
    • Many undesirable effects are due to stimulation of the nicotinic receptors
  • 19.
    • Direct-Acting Agents
    • Reduce intraocular pressure
    • Useful for glaucoma and intraocular surgery
    • Examples: acetylcholine, carbachol, pilocarpine
    • Topical application due to poor oral absorption
  • 20.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Anticholinergics, antihistamines, sympathomimetics
    • Antagonize cholinergic agents, resulting in decreased responses
  • 26.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Drugs that block or inhibit the actions of acetylcholine (ACh) in the parasympathetic nervous system (PSNS)
  • 33.
    • 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.
    • Once these drugs bind to receptors, they inhibit nerve transmission at these receptors.
  • 35.  
  • 36.
    • Natural Synthetic/Semisynthetic
    • atropine anisotropine clidinium
    • belladonna dicyclomine glycopyrrolate
    • hyoscyamine hexocyclium homatropine
    • scopolamine ipratropium isopropamide
    • oxybutynin propantheline
    • tolterodine tridihexethyl
  • 37.
    • 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.
    • 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.
    • 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.
    • CNS
    • Decreased muscle rigidity and muscle tremors
    • Parkinson’s disease
    • Drug-induced extrapyramidal reactions
  • 41.
    • 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.
    • Atropine
    • Used primarily for cardiovascular disorders
    • Sinus node dysfunction
    • Symptomatic second-degree heart block
    • Sinus bradycardia with hemodynamic compromise (advanced life support)
  • 43.
    • 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.
    • Respiratory agents are used to treat:
    • Exercise-induced bronchospasms
    • Chronic bronchitis
    • Asthma
    • Chronic obstructive pulmonary disease
  • 45.
    • 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.
    • Gastrointestinal agents are used to treat:
    • Peptic ulcer disease
    • Irritable bowel disease
    • GI hypersecretory states
  • 47.
    • Genitourinary
    • Relaxed detrusor muscles of the bladder
    • Increased constriction of the internal sphincter
    • Reflex neurogenic bladder
    • Incontinence
  • 48.
    • Body System Side/Adverse Effects
    • Cardiovascular Increased heart rate, dysrhythmias
    • CNS CNS excitation, restlessness, irritability, disorientation, hallucinations, delirium
  • 49.
    • Body System Side/Adverse Effects
    • Eye Dilated pupils, decreased visual accommodation, increased intraocular pressure
    • Gastrointestinal Decreased salivation, decreased gastric secretions, decreased motility
  • 50.
    • Body System Side/Adverse Effects
    • Genitourinary Urinary retention
    • Glandular Decreased sweating
    • Respiratory Decreased bronchial secretions
  • 51.
    • Antihistamines, phenothiazines, tricyclic antidepressants, MAOIs
    • When given with cholinergic blocking agents, cause ADDITIVE cholinergic effects, resulting in increased effects
  • 52.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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)