Chapter 19 AdrenergicBlocking Drugs Copyright 2014 by Mosby

Adrenergic Blockers Bind to adrenergic receptors, but inhibit or block stimulation of the sympathetic nervous system (SNS) Have the opposite effect of adrenergic drugs Inhibit—or lyse—sympathetic stimulation Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2

Adrenergic Blockers (cont’d) Also known as: Adrenergic antagonists Ø Sympatholytics Ø Alpha blockers, beta blockers, or alpha-beta blockers Ø Classified by the type of adrenergic receptor they block Alpha 1 and alpha 2 receptors Ø Beta 1 and beta 2 receptors Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 3

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 4

Drug Effects and Indications: Alpha Blockers Cause both arterial and venous dilation, reducing peripheral vascular resistance and BP Used to treat hypertension Effect on receptors on prostate gland bladder decreases resistance to urinary outflow, thus reducing urinary obstruction and relieving effects of benign prostatic hyperplasia (BPH) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 5

Drug Effects and Indications: Alpha Blockers (cont’d) Used to control and prevent hypertension in patients with pheochromocytoma Phentolamine Quickly reverses the potent vasoconstrictive effects of extravasated vasopressors such as norepinephrine or epinephrine Ø Restores blood flow and prevents tissue necrosis Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 6

Classroom Response Question When phentolamine is used to diagnose the presence of pheochromocytoma, the nurse will assess for what indicative finding? A. Rapid decrease in blood pressure B. Steady increase in blood pressure C. Slower heart rate D. Reduced cardiac ectopy Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 7

Alpha Blockers: Adverse Effects Body System Cardiovascular Adverse Effects Palpitations, orthostatic hypotension, tachycardia, edema, chest pain CNS Dizziness, headache, anxiety, depression, weakness, numbness, fatigue Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 8

Alpha Blockers: Adverse Effects (cont’d) Body System Gastrointestinal Other Adverse Effects Nausea, vomiting, diarrhea, constipation, abdominal pain Incontinence, dry mouth, pharyngitis Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 9

Classroom Response Question When administering an alpha blocker for the first time, it is most important for the nurse to assess the patient for the development of A. B. C. D. renal failure. hypotension. blood dyscrasia. dysrhythmias. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 10

Common Alpha Blockers phenoxybenzamine HCl (Dibenzyline) phentolamine (Regitine) prazosin (Minipress) terazosin (Hytrin) alfuzosin (Uro. Xatral) tamsulosin (Flomax) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 11

Beta Blockers Block stimulation of beta receptors in the SNS Compete with norepinephrine and epinephrine Can be selective or nonselective Nonselective beta blockers block both beta 1 and beta 2 receptors Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 12

Beta Receptors Beta 1 receptors Located primarily on the heart Ø Beta blockers selective for these receptors are called cardioselective beta blockers Ø Beta 2 receptors Ø Located primarily on smooth muscle of bronchioles and blood vessels Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 13

Mechanism of Action Cardioselective beta blockers (beta 1) Reduce SNS stimulation of the heart Ø Decrease heart rate Ø Prolong sinoatrial (SA) node recovery Ø Slow conduction rate through the AV node Ø Decrease myocardial contractility, thus reducing myocardial oxygen demand Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 14

Mechanism of Action (cont’d) Nonselective beta blockers (beta 1 and beta 2) Cause same effects on heart as cardioselective beta blockers Ø Constrict bronchioles, resulting in narrowing of airways and shortness of breath Ø Produce vasoconstriction of blood vessels Ø Other effects Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 15

Indications Angina Ø Cardioprotective Ø Inhibits stimulation from circulating catecholamines Dysrhythmias Ø Decreases demand for myocardial oxygen Class II antidysrhythmic Migraine headache Ø Lipophilicity allows entry into CNS Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 16

Classroom Response Question A 58 -year-old patient is recovering in the intensive care unit after a myocardial infarction (MI). The nurse notes an order for the beta blocker metoprolol (Lopressor). The purpose of this drug is to A. dilate the coronary arteries. B. inhibit stimulation of the myocardium by circulating catecholamines. C. provide a positive inotropic effect. D. maintain the patient’s blood pressure. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 17

Indications (cont’d) Antihypertensive Heart failure Glaucoma (topical use) Copyright © 2014 by Mosby, an

Adverse Effects: Beta Blockers Body System Blood Adverse Effects Agranulocytosis, thrombocytopenia Cardiovascular AV block, bradycardia, heart failure CNS Dizziness, depression, unusual dreams, drowsiness Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 19

Adverse Effects: Beta Blockers Body System Gastrointestinal Adverse Effects Nausea, vomiting, constipation, diarrhea Other Impotence, alopecia, wheezing, bronchospasm, dry mouth Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 20

Adverse Effects: Beta Blockers (cont’d) Nonselective beta blockers may interfere with normal responses to hypoglycemia (tremor, tachycardia, nervousness) May mask signs and symptoms of hypoglycemia Ø Use with caution in patients with diabetes mellitus Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 21

Classroom Response Question The nurse knows that the adverse effects of a nonselective beta blocker are likely to be the most immediately life threatening in which patient? A. Patient with type I diabetes B. Patient with asthma C. Patient with gastroesophageal reflux disease D. Patient with hypertension Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 22

Beta Blockers: Examples atenolol (Tenormin) carvedilol (Coreg) esmolol (Brevibloc) labetalol (Normodyne) metoprolol (Lopressor) propranolol (Inderal) sotalol (Betapace) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 23

Adrenergic-Blocking Drugs: Nursing Implications Assess for allergies and history of COPD, hypotension, cardiac dysrhythmias, bradycardia, heart failure, or other cardiovascular problems Ø Any preexisting condition that might be exacerbated by the use of these drugs might be a contraindication to their use Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 24

Adrenergic-Blocking Drugs: Nursing Implications (cont’d) Remember that alpha blockers may precipitate hypotension Remember that some beta blockers may precipitate bradycardia, hypotension, heart block, heart failure, and bronchoconstriction Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 25

Adrenergic-Blocking Drugs: Nursing Implications (cont’d) Avoid over-the-counter medications because of possible interactions Possible drug interactions may occur with: Ø Ø Ø Antacids (aluminum hydroxide type) Antimuscarinics/anticholinergics Diuretics and cardiovascular drugs Neuromuscular blocking drugs Oral hypoglycemic drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 26

Adrenergic-Blocking Drugs: Nursing Implications (cont’d) Encourage patients to take medications as prescribed Instruct patients that these medications should never be stopped abruptly Inform patients to report constipation or the development of urinary hesitancy or bladder distention Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 27

Adrenergic-Blocking Drugs: Nursing Implications (cont’d) Teach patients to change positions slowly to prevent or minimize postural hypotension Instruct patients to avoid caffeine (excessive irritability) Instruct patients to avoid alcohol ingestion and hazardous activities until blood levels become stable Instruct patients to notify their physician if palpitations, dyspnea, nausea, or vomiting occurs Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 28

Adrenergic-Blocking Drugs: Nursing Implications (cont’d) Monitor for adverse effects Monitor for therapeutic effects Decreased chest pain in patients with angina Ø Return to normal BP and HR Ø Other specific effects, depending on the use Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 29

Classroom Response Question A patient with type 2 diabetes is taking a beta blocker as part of treatment for hypertension. Which complication is most likely to develop? A. Hypertension B. Hyperkalemia C. Hypoglycemia D. Angina Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 30

Beta-Blocking Drugs: Nursing Implications Rebound hypertension or chest pain may occur if this medication is discontinued abruptly Instruct patients to notify their physician if they become ill and unable to take medication Inform patients that they may notice a decrease in tolerance for exercise (dizziness and fainting may occur with increased activity), and have patients notify the physician if these problems occur Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 31

Beta-Blocking Drugs: Nursing Implications (cont’d) Inform patients to report the following to their physician: Weight gain of more than 2 pounds in 1 day or 5 pounds in 1 week Ø Edema of the feet or ankles Ø Shortness of breath Ø Excessive fatigue or weakness Ø Syncope or dizziness Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 32