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Instructors may wish to Instructors may wish to insert EIC Image #57: insert EIC Image #57:
The Sympathetic, Parasympathetic, The Sympathetic, Parasympathetic, and Somatic Nervous Systemsand Somatic Nervous Systems
This slide illustrates location of the nicotinic This slide illustrates location of the nicotinic and muscarinic receptors within the PSNS.and muscarinic receptors within the PSNS.
Drug Effects of Cholinergic AgentsDrug Effects of Cholinergic Agents
• At recommended doses, the cholinergics At recommended doses, the cholinergics primarily affect the MUSCARINIC receptors.primarily affect the MUSCARINIC receptors.
• At high doses, cholinergics stimulate the At high doses, cholinergics stimulate the NICOTINIC receptors. NICOTINIC receptors.
• Keep in mind that these agents will stimulate Keep in mind that these agents will stimulate the PSNS and mimic the action of ACh. the PSNS and mimic the action of ACh.
• Assess for allergies, presence of GI or GU Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, obstructions, asthma, peptic ulcer disease, or coronary artery disease.or coronary artery disease.
• Perform baseline assessment of VS and Perform baseline assessment of VS and systems overview.systems overview.
• Medications should be taken as ordered Medications should be taken as ordered and not abruptly stopped. and not abruptly stopped.
• The doses should be spread evenly apart The doses should be spread evenly apart to optimize the effects of the medication.to optimize the effects of the medication.
• Overdosing can cause life-threatening Overdosing can cause life-threatening problems. Patients should not adjust the problems. Patients should not adjust the dosages unless directed by the physician.dosages unless directed by the physician.
• Encourage patients with myasthenia gravis to Encourage patients with myasthenia gravis to take medication 30 minutes before eating to take medication 30 minutes before eating to help improve chewing and swallowing.help improve chewing and swallowing.
• When donepezil is prescribed for Alzheimer’s When donepezil is prescribed for Alzheimer’s disease, be honest with caregivers and disease, be honest with caregivers and patients that the drug is for management patients that the drug is for management of symptoms, not for a cure.of symptoms, not for a cure.
• Therapeutic effects of donepezil may not Therapeutic effects of donepezil may not occur for up to 6 weeks.occur for up to 6 weeks.
• Atropine is the antidote for cholinergics. Atropine is the antidote for cholinergics. It should be available in the patient’s room It should be available in the patient’s room for immediate use if needed.for immediate use if needed.
• Patients should notify their physician if they Patients should notify their physician if they experience muscle weakness, abdominal experience muscle weakness, abdominal cramps, diarrhea, or difficulty breathing.cramps, diarrhea, or difficulty breathing.
Cholinergic Agents: Cholinergic Agents: Nursing ImplicationsNursing ImplicationsMonitor for therapeutic effects:Monitor for therapeutic effects:
• Alleviated signs and symptoms of myasthenia gravisAlleviated signs and symptoms of myasthenia gravis
• In postoperative patients with decreased GI peristalsis, In postoperative patients with decreased GI peristalsis, look for:look for:
– Increased bowel soundsIncreased bowel sounds
– Passage of flatusPassage of flatus
– Occurrence of bowel movementsOccurrence of bowel movements
• In patients with urinary retention/hypotonic bladder, In patients with urinary retention/hypotonic bladder, urination should occur within 60 minutes of bethanecol urination should occur within 60 minutes of bethanecol administrationadministration
• Drugs that block or inhibit the actions of Drugs that block or inhibit the actions of acetylcholine (ACh) in the parasympathetic acetylcholine (ACh) in the parasympathetic nervous system (PSNS)nervous system (PSNS)
Cholinergic Blocking Agents: Cholinergic Blocking Agents: Mechanism of ActionMechanism of Action
• Competitive antagonistsCompetitive antagonists
• Compete with AChCompete with ACh
• Block ACh at the muscarinic receptors Block ACh at the muscarinic receptors in the PSNSin the PSNS
– As a result, ACh is unable to bind to theAs a result, ACh is unable to bind to thereceptor site and cause a cholinergic effect.receptor site and cause a cholinergic effect.
Cholinergic Blocking Agents: Cholinergic Blocking Agents: Mechanism of ActionMechanism of Action
• Once these drugs bind to receptors, they Once these drugs bind to receptors, they inhibit nerve transmission at these receptors.inhibit nerve transmission at these receptors.
Affect the heart’s conduction systemAffect the heart’s conduction system
• Low doses: slow the heart rateLow doses: slow the heart rate
• High doses: block inhibitory vagal effects on High doses: block inhibitory vagal effects on the SA and AV node pacemaker cellsthe SA and AV node pacemaker cells
Cholinergic Blocking Agents: Cholinergic Blocking Agents: Therapeutic Uses Therapeutic Uses RespiratoryRespiratoryBlocking the cholinergic stimulation of the PSNS Blocking the cholinergic stimulation of the PSNS
allows unopposed action of the SNS.allows unopposed action of the SNS.
• Results:Results:
– Decreased secretions from nose, mouth, Decreased secretions from nose, mouth, pharynx, bronchipharynx, bronchi
– Relaxed smooth muscles in bronchi Relaxed smooth muscles in bronchi and bronchiolesand bronchioles
PSNS controls gastric secretions and smooth PSNS controls gastric secretions and smooth muscles that produce gastric motility.muscles that produce gastric motility.
• Blockade of PSNS results in:Blockade of PSNS results in:
– Decreased secretionsDecreased secretions
– Relaxation of smooth muscleRelaxation of smooth muscle
– Decreased GI motility and peristalsisDecreased GI motility and peristalsis
• When given with cholinergic blocking When given with cholinergic blocking agents, cause ADDITIVE cholinergic agents, cause ADDITIVE cholinergic effects, resulting in increased effectseffects, resulting in increased effects
• Keep in mind that these agents will blockKeep in mind that these agents will blockthe action of ACh in the PSNS.the action of ACh in the PSNS.
• Assess for allergies, presence of BPH, Assess for allergies, presence of BPH, glaucoma, tachycardia, MI, CHF, hiatal glaucoma, tachycardia, MI, CHF, hiatal hernia, and GI or GU obstruction.hernia, and GI or GU obstruction.
• Perform baseline assessment of VS Perform baseline assessment of VS and systems overview.and systems overview.
• Medications should be taken exactly as prescribed Medications should be taken exactly as prescribed to have the maximum therapeutic effect.to have the maximum therapeutic effect.
• Overdosing can cause life-threatening problems. Overdosing can cause life-threatening problems.
• Blurred vision may cause problems with driving Blurred vision may cause problems with driving or operating machinery.or operating machinery.
• Patients may experience sensitivity to light and Patients may experience sensitivity to light and may want to wear dark glasses or sunglasses.may want to wear dark glasses or sunglasses.
• When giving ophthalmic solutions, apply pressure to When giving ophthalmic solutions, apply pressure to the inner canthus to prevent systemic absorption.the inner canthus to prevent systemic absorption.
• Dry mouth may occur; can be handled by chewing Dry mouth may occur; can be handled by chewing gum, frequent mouth care, and hard candy.gum, frequent mouth care, and hard candy.
• Check with physician before taking any other Check with physician before taking any other medication, including OTC medications.medication, including OTC medications.
• ANTIDOTE for atropine is physostigmine salicylate ANTIDOTE for atropine is physostigmine salicylate (Antilirium).(Antilirium).
• Anticholinergics may lead to higher risk for Anticholinergics may lead to higher risk for heat stroke due to effects on heat-regulating heat stroke due to effects on heat-regulating mechanisms. mechanisms.
• Teach patients to limit physical exertion, and Teach patients to limit physical exertion, and avoid high temperatures and strenuous avoid high temperatures and strenuous exercise.exercise.
• Emphasize the importance of adequate fluid Emphasize the importance of adequate fluid and salt intake.and salt intake.
• Patients should report the following to their Patients should report the following to their physician: urinary hesitancy and/or retention, physician: urinary hesitancy and/or retention, constipation, palpitations, tremors, confusion, constipation, palpitations, tremors, confusion, sedation or amnesia, excessive dry mouth sedation or amnesia, excessive dry mouth (especially if they have chronic lung (especially if they have chronic lung infections or disease), or feverinfections or disease), or fever
• Monitor for therapeutic effects:Monitor for therapeutic effects:
• For patients with Parkinson’s disease: For patients with Parkinson’s disease: fewer tremors and decreased salivation fewer tremors and decreased salivation and droolingand drooling
• For patients with peptic ulcer disease: For patients with peptic ulcer disease: decreased abdominal paindecreased abdominal pain