Chapter 28 Diuretic Drugs Copyright 2014 by Mosby

Diuretic Drugs that accelerate the rate of urine formation Result in the removal of sodium and water Used in the treatment of hypertension, heart failure, and renal failure Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2

Sodium In the nephron, where sodium goes, water follows 60% to 70% of sodium and water is returned to bloodstream by the proximal tubule Ø 20% to 25% of all sodium is reabsorbed into the bloodstream in the ascending loop of Henle Ø 5% to 10% is reabsorbed in the distal tubules Ø 3% is reabsorbed in collecting ducts Ø If water is not absorbed, it is excreted as urine Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 3

The Nephron and Diuretic Sites of Action Copyright © 2014 by Mosby, an imprint

Classroom Response Question Which location is the area where the highest percentage of sodium and water are resorbed back into the bloodstream? A. Glomerulus B. Proximal tubule C. Ascending loop of Henle D. Distal tubule Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 5

Types of Diuretic Drugs Carbonic anhydrase inhibitors Loop diuretics Osmotic diuretics Potassium-sparing diuretics Thiazide and thiazide-like diuretics Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 6

Carbonic Anhydrase Inhibitors (CAIs) acetazolamide (Diamox) Ø Most commonly used CAI Copyright © 2014

Carbonic Anhydrase Inhibitors: Mechanism of Action The enzyme carbonic anhydrase helps to make H+ ions available for exchange with sodium and water in the proximal tubules CAIs block the action of carbonic anhydrase, thus preventing the exchange of H+ ions with sodium and water Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 8

Carbonic Anhydrase Inhibitors: Mechanism of Action (cont’d) Inhibition of carbonic anhydrase reduces H+ ion concentration in renal tubules As a result, there is increased excretion of bicarbonate, sodium, water, and potassium Resorption of water is decreased, and urine volume is increased Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 9

Carbonic Anhydrase Inhibitors: Indications Adjunct drugs in the long-term management of open-angle glaucoma Used with miotics to lower intraocular pressure before ocular surgery in certain cases Also useful in the treatment of: Edema Ø High-altitude sickness Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 10

Carbonic Anhydrase Inhibitors: Indications (cont’d) Acetazolamide (Diamox) is used in the management of edema secondary heart failure (HF) when other diuretics are not effective CAIs are less potent diuretics than loop diuretics or thiazides—the metabolic acidosis they induce reduces their diuretic effect in 2 to 4 days Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 11

Carbonic Anhydrase Inhibitors: Adverse Effects Metabolic acidosis Anorexia Hematuria Photosensitivity Melena Hypokalemia Drowsiness Paresthesias Urticaria Glycosuria in diabetic patients Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 12

Loop Diuretics bumetanide (Bumex) ethacrynic acid (Edecrin) furosemide (Lasix) torsemide (Demadex) Copyright © 2014

Loop Diuretics: Mechanism of Action Possess renal, cardiovascular, and metabolic effects Act directly on the ascending limb of the loop of Henle to inhibit chloride and sodium resorption Increase renal prostaglandins, resulting in the dilation of blood vessels and reduced peripheral vascular resistance Useful in treatment of edema Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 14

Loop Diuretics: Drug Effects Potent diuresis and subsequent loss of fluid Decreased fluid volume causes a reduction in: Blood pressure Ø Pulmonary vascular resistance Ø Systemic vascular resistance Ø Central venous pressure Ø Left ventricular end-diastolic pressure Ø Potassium and sodium depletion Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 15

Loop Diuretics: Indications Edema associated with HF or hepatic or renal disease To control hypertension To increase renal excretion of calcium in patients with hypercalcemia In cases of HF resulting from diastolic dysfunction Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 16

Loop Diuretics: Adverse Effects Body System Adverse Effects Central nervous system (CNS) Dizziness, headache, tinnitus, blurred vision Gastrointestinal (GI) Nausea, vomiting, diarrhea Integumentary Stevens-Johnson syndrome (torsemide) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 17

Loop Diuretics: Adverse Effects (cont’d) Body System Hematologic Adverse Effects Agranulocytosis, neutropenia, thrombocytopenia Metabolic Hypokalemia, hyperglycemia, hyperuricemia Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 18

Classroom Response Question When administering a loop diuretic to a patient, it is most important for the nurse to determine if the patient is also taking which drug? A. lithium (Eskalith) B. acetaminophen (Tylenol) C. penicillin D. theophylline Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 19

Osmotic Diuretics mannitol (Osmitrol) Ø Most used osmotic diuretic Urea Organic acids Glucose Copyright

Osmotic Diuretics: Mechanism of Action Work mostly in the proximal tubule Nonabsorbable, producing an osmotic effect Pull water into the renal tubules from the surrounding tissues Inhibit tubular resorption of water and solutes, thus producing rapid diuresis Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 21

Osmotic Diuretics: Drug Effects Increases glomerular filtration rate and renal plasma flow—helps to prevent kidney damage during acute renal failure Reduces intracranial pressure or cerebral edema associated with head trauma Reduces excessive intraocular pressure Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 22

Osmotic Diuretics: Indications Treatment of patients in the early, oliguric phase of acute renal failure (ARF) To promote excretion of toxic substances To reduce intracranial pressure Treatment of cerebral edema NOT indicated for peripheral edema Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 23

Osmotic Diuretics: Adverse Effects Convulsions Thrombophlebitis Pulmonary congestion Also headaches, chest pains, tachycardia, blurred vision, chills, and fever Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 24

Osmotic Diuretics: Mannitol (Osmitrol) Intravenous infusion only May crystallize when exposed to low temperatures

Classroom Response Question While preparing an infusion of mannitol (Osmitrol), the nurse notices small crystals in the IV tubing. The most appropriate action by the nurse is to A. administer the infusion slowly. B. discard the solution and obtain another bag of medication. C. obtain a filter, and then infuse the solution. D. return the fluid to the IV bag to dissolve the crystals. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 26

Potassium-Sparing Diuretics amiloride (Midamor) spironolactone (Aldactone) triamterene (Dyrenium) Also known as aldosterone-inhibiting diuretics Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 27

Potassium-Sparing Diuretics: Mechanism of Action Work in collecting ducts and distal convoluted tubules Interfere with sodium-potassium exchange Competitively bind to aldosterone receptors Block resorption of sodium and water usually induced by aldosterone Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 28

Potassium-Sparing Diuretics: Drug Effects Prevent potassium from being pumped into the tubule, thus preventing its secretion Competitively block aldosterone receptors and inhibit their action Promote the excretion of sodium and water Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 29

Potassium-Sparing Diuretics: Indications spironolactone and triamterene Hyperaldosteronism Ø Hypertension Ø Reversing potassium loss caused by potassium-losing drugs Ø Certain cases of HF Ø amiloride Ø Treatment of HF Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 30

Potassium-Sparing Diuretics: Adverse Effects Body System Adverse Effects CNS Dizziness, headache GI Cramps, nausea, vomiting, diarrhea Other Urinary frequency, weakness, hyperkalemia Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 31

Potassium-Sparing Diuretics: Adverse Effects (cont’d) spironolactone (Aldactone) Gynecomastia Amenorrhea Irregular menses Postmenopausal bleeding Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 32

Thiazide and Thiazide-like Diuretics Thiazide diuretics hydrochlorothiazide (Esidrix, Hydro. DIURIL) Ø chlorothiazide (Diuril) Ø Thiazide-like diuretics metolazone (Mykrox, Zaroxolyn) Ø chlorthalidone (Hydone, Thalitone) Ø indapamide (Lozol) Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 33

Thiazide and Thiazide-like Diuretics: Mechanism of Action Inhibit tubular resorption of sodium, chloride, and potassium ions Action primarily in the distal convoluted tubule Result: water, sodium, and chloride are excreted Potassium is also excreted to a lesser extent Dilate the arterioles by direct relaxation Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 34

Thiazide and Thiazide-like Diuretics: Drug Effects Lowered peripheral vascular resistance Depletion of sodium and

Thiazide and Thiazide-like Diuretics (cont’d) Thiazides should not be used if creatinine clearance is less than 30 to 50 m. L/min (normal is 125 m. L/min) Metolazone remains effective to a creatinine clearance of 10 m. L/min Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 36

Thiazide and Thiazide-like Diuretics: Indications Hypertension (one of the most prescribed group of drugs for this) Edematous states Idiopathic hypercalciuria Diabetes insipidus Heart failure due to diastolic dysfunction Adjunct drugs in treatment of edema related to HF, hepatic cirrhosis, or corticosteroid or estrogen therapy Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 37

Thiazide and Thiazide-like Diuretics: Adverse Effects Body System CNS Adverse Effects Dizziness, headache, blurred vision GI Anorexia, nausea, vomiting, diarrhea GU Impotence Hematologic Jaundice, leukopenia Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 38

Thiazide and Thiazide-like Diuretics: Adverse Effects (cont’d) Body System Integumentary Adverse Effects Urticaria, photosensitivity Metabolic Hypokalemia, hyperglycemia, hyperuricemia, hypochloremic alkalosis Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 39

Nursing Implications Perform a thorough patient history and physical examination Assess baseline fluid volume status, intake and output, serum electrolyte values, weight, and vital signs—especially postural BPs Assess for disorders that may contraindicate or necessitate cautious use of these drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 40

Nursing Implications (cont’d) Instruct patients to take the medication in the morning if possible to avoid interference with sleep patterns Monitor serum potassium levels during therapy Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 41

Nursing Implications (cont’d) Teach patients to maintain proper nutritional and fluid volume status Teach patients to eat more potassium-rich foods when taking any but the potassium-sparing drugs Foods high in potassium include bananas, oranges, dates, apricots, raisins, broccoli, green beans, potatoes, meats, fish, and legumes Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 42

Nursing Implications (cont’d) Patients taking diuretics along with a digitalis preparation should be taught to monitor for digitalis toxicity Patients with diabetes mellitus who are taking thiazide and/or loop diuretics should be told to monitor blood glucose and watch for elevated levels Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 43

Nursing Implications (cont’d) Teach patients to change positions slowly and to rise slowly after sitting or lying to prevent dizziness and fainting related to orthostatic hypotension Encourage patients to keep a log of their daily weight Remind patients to return for follow-up visits and lab work Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 44

Nursing Implications (cont’d) Patients who have been ill with nausea, vomiting, and/or diarrhea should notify their primary care provider because fluid and electrolyte imbalances can result Signs and symptoms of hypokalemia include muscle weakness, constipation, irregular pulse rate, and overall feeling of lethargy Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 45

Nursing Implications (cont’d) Instruct patients to notify their primary care provider immediately if they experience rapid heart rates or syncope (reflects hypotension or fluid loss) Excessive consumption of licorice can lead to additive hypokalemia in patients taking thiazides Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 46

Nursing Implications (cont’d) Monitor for adverse effects Ø Metabolic alkalosis, drowsiness, lethargy, hypokalemia, tachycardia, hypotension, leg cramps, restlessness, decreased mental alertness Monitor for hyperkalemia with potassium-sparing diuretics Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 47

Nursing Implications (cont’d) Monitor for therapeutic effects Reduction of edema Ø Reduction of fluid volume overload Ø Improvement in manifestations of heart failure Ø Reduction of hypertension Ø Return to normal intraocular pressures Ø Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 48

Case Study A patient with a creatinine clearance of 20 m. L/min is admitted to the medical surgical unit. The patient is in need of rapid diuresis. Which class of diuretic does the nurse anticipate administering? A. B. C. D. Potassium-sparing Thiazide Osmotic Loop Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 49

Case Study (cont’d) The patient is ordered furosemide (Lasix). Before administering furosemide, it is most important for the nurse to assess the patient for allergies to which drug class? A. B. C. D. Aminoglycosides Sulfonamides Macrolides Penicillins Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 50

Case Study (cont’d) Two days after admission, the nurse is reviewing laboratory results of the patient. Which is the most common electrolyte finding resulting from the administration of furosemide (Lasix)? A. B. C. D. Hypocalcemia Hypophosphatemia Hypokalemia Hypomagnesemia Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 51

Case Study (cont’d) The patient is being discharged home with furosemide (Lasix). When providing discharge teaching, which instruction will the nurse include? A. B. C. D. Avoid prolonged exposure to the sun. Avoid foods high in potassium content. Stop taking the medication if you feel dizzy. Weigh yourself once a week and report a gain or loss of more than 1 pound. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 52