Cholinergic-Blocking Drugs Chapter 21 Cholinergic-Blocking Drugs Copyright © 2017, Elsevier Inc. All rights reserved.

Cholinergic-Blocking Drugs Drugs that block or inhibit the actions of acetylcholine (ACh) in the parasympathetic nervous system (PSNS) Also known as anticholinergics, parasympatholytics, and antimuscarinic drugs Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Mechanism of Action Competitive antagonists Compete with ACh for binding at muscarinic receptors in the PSNS As a result, ACh is unable to bind to the receptor site and cause a cholinergic effect. When these drugs bind to receptors, they inhibit nerve transmission at these receptors. Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Site of action of cholinergic blockers in the parasympathetic nervous system. ACh, Acetylcholine Copyright © 2017, Elsevier Inc. All rights reserved.

Cholinergic-Blocking Drugs: Examples atropine dicyclomine (Bentyl) glycopyrrolate (Robinul) oxybutynin (Ditropan) scopolamine (Transderm-Scōp) tolterodine (Detrol) Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Drug Effects Cardiovascular Small doses: decrease heart rate Large doses: increase heart rate Central nervous system (CNS) Small doses: decrease muscle rigidity and tremors Large doses: drowsiness, disorientation, hallucinations Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Drug Effects (Cont.) Eye Dilated pupils (mydriasis) Decreased accommodation caused by paralysis of ciliary muscles (cycloplegia) Gastrointestinal (GI) Relax smooth muscle tone of GI tract Decrease intestinal and gastric secretions Decrease motility and peristalsis Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question Which finding would the nurse anticipate when assessing a patient with an atropine overdose? Moist skin Miosis Bradycardia Urinary retention Correct answer: D Rationale: Atropine overdose is manifested by flushing, dry skin and mucous membranes, mydriasis, altered mental status, and fever. Other serious effects include sinus tachycardia, urinary retention, hypertension, hallucinations, and cardiovascular collapse. Activated charcoal is usually given along with supportive therapy. Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Drug Effects (Cont.) Genitourinary (GU) Relaxed detrusor muscle Increased constriction of internal sphincter Result: urinary retention Glandular Decreased bronchial secretions, salivation, sweating Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Drug Effects (Cont.) Respiratory Decreased bronchial secretions Dilated bronchial airways Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Central Nervous System Decreasing muscle rigidity and muscle tremors Parkinson’s disease Drug-induced extrapyramidal reactions such as those associated with antipsychotic drugs Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Cardiovascular Affects the heart’s conduction system Low doses: slow the heart rate High doses: block inhibitory vagal effects on sinoatrial and atrioventricular node pacemaker cells Results in increased heart rate Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Cardiovascular (Cont.) Atropine Used primarily for cardiovascular disorders Diagnosis of sinus node dysfunction Symptomatic second-degree heart block Severe sinus bradycardia with hemodynamic compromise (advanced life support) Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Respiratory Blocking the cholinergic stimulation of the PSNS allows unopposed action of the SNS. Results Decreased secretions from the nose, mouth, pharynx, and bronchi Relaxed smooth muscles in the bronchi and bronchioles Decreased airway resistance Bronchodilation Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Respiratory (Cont.) Cholinergic blockers are used to treat: Exercise-induced bronchospasms Chronic bronchitis Asthma Chronic obstructive pulmonary disease Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Gastrointestinal The 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 Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Gastrointestinal (Cont.) GI drugs are used to treat: Irritable bowel disease GI hypersecretory states Copyright © 2017, Elsevier Inc. All rights reserved.

Indications: Genitourinary Reflex neurogenic bladder Incontinence Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question Glycopyrrolate (Robinul) and an opioid are administered to a patient before surgery in the preoperative area. The anticholinergic is used to potentiate the action of the opioid. assist the patient in retaining urine during surgery. control secretions during surgery. prevent nausea. Correct answer: C Rationale: Anticholinergics such as glycopyrrolate and atropine are given preoperatively to reduce or control secretions before and during surgery. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Copyright © 2017, Elsevier Inc. All rights reserved. Contraindications Known drug allergy Angle-closure glaucoma Acute asthma or other respiratory distress Myasthenia gravis Acute cardiovascular instability GI or GU tract obstruction (e.g., benign prostatic hyperplasia [BPH]) Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Adverse Effects Body System Adverse Effects Cardiovascular CNS Increased heart rate, dysrhythmias CNS excitation, restlessness, irritability, disorientation, hallucinations, delirium Copyright © 2017, Elsevier Inc. All rights reserved.

Adverse Effects (Cont.) Body System Adverse Effects Eye GI Dilated pupils (causing blurred vision), increased intraocular pressure Decreased salivation, decreased gastric secretions, decreased motility (causing constipation) Copyright © 2017, Elsevier Inc. All rights reserved.

Adverse Effects (Cont.) Body System Adverse Effects GU Glandular Respiratory Urinary retention Decreased sweating Decreased bronchial secretions Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question Before administering tolterodine (Detrol), it is most important for the nurse to assess the patient for a history of which condition? Angle-closure glaucoma Cataracts Hypothyroidism Hyponatremia Correct answer: A Rationale: Tolterodine (Detrol) may worsen preexisting angle-closure glaucoma and urinary retention, so its use should be avoided in patients with these conditions. Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Toxicity and Overdose Symptomatic and supportive therapy Continuous electrocardiographic monitoring Activated charcoal Treatment of shock Physostigmine Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Interactions Amantadine, antihistamines, phenothiazines, tricyclic antidepressants, digoxin When given with other cholinergic blocking drugs, cause additive cholinergic effects, resulting in increased effects Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Atropine Naturally occurring antimuscarinic Uses: bradycardia, ventricular asystole, antidote for anticholinesterase inhibitor toxicity or poisoning, and preoperatively to reduce salivation and GI secretions Contraindications: angle-closure glaucoma, advanced hepatic and renal dysfunction, hiatal hernia associated with reflux esophagitis, intestinal atony, obstructive GI or GU conditions, and severe ulcerative colitis Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Bentyl Synthetic antispasmodic cholinergic blocker Uses: functional disturbances of GI motility such as irritable bowel syndrome. Contraindications: known hypersensitivity to anticholinergics, angle-closure glaucoma, GI tract obstruction, myasthenia gravis, paralytic ileus, GI atony, and toxic megacolon Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Rubinol Synthetic antimuscarinic drug Blocks receptor sites in the autonomic nervous system that control the production of secretions Use: preoperatively to reduce salivation and excessive secretions in the respiratory and GI tracts Contraindications: hypersensitivity, angle-closure glaucoma, myasthenia gravis, GI or GU tract obstruction, tachycardia, myocardial ischemia, hepatic disease, ulcerative colitis, and toxic megacolon Copyright © 2017, Elsevier Inc. All rights reserved.

Oxybutynin (Ditropan) Synthetic antimuscarinic drug Uses: overactive bladder and antispasmodic for neurogenic bladder associated with spinal cord injuries and congenital conditions such as spina bifida Contraindications: drug allergy, urinary or gastric retention, and uncontrolled angle-closure glaucoma Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Scopolamine Naturally occurring cholinergic blocker and one of the principal belladonna alkaloids Uses: prevention of motion sickness and to help prevent postoperative, postanesthesia nausea and vomiting Contraindications: angle-closure glaucoma, advanced hepatic and renal dysfunction, hiatal hernia associated with reflux esophagitis, intestinal atony, obstructive GI or GU conditions, and severe ulcerative colitis Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Scopolamine (Cont.) Adverse effects: drowsiness, dry mouth, and blurred vision Using scopolamine with CNS depressants or alcohol may increase sedation. Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Tolterodine (Detrol) Muscarinic receptor blocker Uses: urinary frequency, urgency, and urge incontinence caused by bladder (detrusor) overactivity Newer drugs for this purpose include solifenacin (Vesicare), darifenacin (Enablex), trospium (Sanctura), and fesoterodine (Toviaz). Newer drugs are associated with a much lower incidence of dry mouth, partly because of their pharmacologic specificity for the bladder as opposed to the salivary glands. Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Mirabegron Used to treat overactive bladder Beta3 agonist; represents a new class of therapy for this condition Does not have same side effects as other drugs to treat overactive bladder Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Nursing Implications Keep in mind that these drugs block the action of ACh in the PSNS. Assess for allergies, presence of BPH, urinary retention, glaucoma, tachycardia, myocardial infarction, heart failure, hiatal hernia, and GI or GU obstruction. Perform baseline assessment of vital signs and systems overview. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Medications should be taken exactly as prescribed to have the maximum therapeutic effect. Overdosing can cause life-threatening problems. Blurred vision will cause problems with driving or operating machinery. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Patients may experience sensitivity to light and may want to wear dark glasses or sunglasses. When giving ophthalmic solutions, apply pressure to the inner canthus to prevent systemic absorption. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Dry mouth may occur; can be handled by chewing gum, frequent mouth care, and hard candy. Patients should check with the physician before taking any other medication, including over-the-counter medications. Antidote for atropine overdose is physostigmine. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Anticholinergics taken by older adult patients may lead to higher risk for heatstroke because of the 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. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Patients should report the following symptoms to their physician: urinary hesitancy or retention, constipation, tachycardia, palpitations, tremors, confusion, sedation, hallucinations, and decreased sweating (leading to hot, dry skin). Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Monitor for therapeutic effects. For patients with Parkinson’s disease: fewer tremors and decreased salivation and drooling For patients with urologic problems: improved urinary patterns, less hypermotility, increased time between voiding Monitor for adverse effects. Copyright © 2017, Elsevier Inc. All rights reserved.