Cholinergic-Blocking Drugs Chapter 21 Cholinergic-Blocking Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

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 © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 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 Once these drugs bind to receptors, they inhibit nerve transmission at these receptors Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Cholinergic-Blocking Drugs: Examples atropine dicyclomine (Bentyl) glycopyrrolate (Robinul) oxybutynin (Ditropan) scopolamine (Transderm-Scōp) tolterodine (Detrol) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Drug Effects Cardiovascular Small doses: decrease heart rate Large doses: increase heart rate CNS Small doses: decrease muscle rigidity and tremors Large doses: drowsiness, disorientation, hallucinations Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Drug Effects (cont’d) Eye Dilated pupils (mydriasis) Decreased accommodation caused by paralysis of ciliary muscles (cycloplegia) Gastrointestinal Relax smooth muscle tone of GI tract Decrease intestinal and gastric secretions Decrease motility and peristalsis Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Classroom Response 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 © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Drug Effects (cont’d) Genitourinary Relaxed detrusor muscle Increased constriction of internal sphincter Result: urinary retention Glandular Decreased bronchial secretions, salivation, sweating Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Drug Effects (cont’d) Respiratory Decreased bronchial secretions Dilated bronchial airways Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Indications: CNS Decreasing muscle rigidity and muscle tremors Parkinson’s disease Drug-induced extrapyramidal reactions Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: Cardiovascular Affects the heart’s conduction system Low doses: slow the heart rate High doses: block inhibitory vagal effects on sinoatrial (SA) and atrioventricular (AV) node pacemaker cells Results in increased heart rate Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: Cardiovascular (cont’d) 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 © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: 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 Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: Respiratory (cont’d) Cholinergic blockers are used to treat: Exercise-induced bronchospasms Chronic bronchitis Asthma Chronic obstructive pulmonary disease Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: 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 Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: Gastrointestinal (cont’d) Gastrointestinal drugs are used to treat: Irritable bowel disease GI hypersecretory states Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Indications: Genitourinary Reflex neurogenic bladder Incontinence Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Classroom Response Question Glycopyrrolate (Robinul) and an opioid are administered to a patient prior to 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 © 2014 by Mosby, an imprint of Elsevier Inc. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Indications Acute pancreatitis: reduces gastric and pancreatic secretions Preoperatively: reduces salivary secretions Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Adverse Effects Body System Adverse Effects Cardiovascular CNS Increased heart rate, dysrhythmias CNS excitation, restlessness, irritability, disorientation, hallucinations, delirium Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Adverse Effects (cont’d) Body System Adverse Effects Eye Gastrointestinal Dilated pupils (causing blurred vision), increased intraocular pressure Decreased salivation, decreased gastric secretions, decreased motility (causing constipation) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Adverse Effects (cont’d) Body System Adverse Effects Genitourinary Glandular Respiratory Urinary retention Decreased sweating Decreased bronchial secretions Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Classroom Response Question Prior to 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 pre-existing angle-closure glaucoma and urinary retention, so its use should be avoided in patients with these conditions. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Interactions Amantadine, antihistamines, phenothiazines, tricyclic antidepressants, digoxin When given with other cholinergic blocking drugs, cause additive cholinergic effects, resulting in increased effects Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 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, MI, HF, hiatal hernia, and GI or GU obstruction Perform baseline assessment of vital signs and systems overview Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Nursing Implications (cont’d) 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 © 2014 by Mosby, an imprint of Elsevier Inc.

Nursing Implications (cont’d) 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 © 2014 by Mosby, an imprint of Elsevier Inc.

Nursing Implications (cont’d) 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 over-the-counter medications Antidote for atropine overdose is physostigmine Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Nursing Implications (cont’d) Anticholinergics taken by the elderly patient 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 © 2014 by Mosby, an imprint of Elsevier Inc.

Nursing Implications (cont’d) Patients should report the following symptoms to their physician: urinary hesitancy and/or retention, constipation, tachycardia, palpitations, tremors, confusion, sedation, hallucinations, decreased sweating (leading to hot, dry skin) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Nursing Implications (cont’d) 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 © 2014 by Mosby, an imprint of Elsevier Inc.