Copyright © 2017, Elsevier Inc. All rights reserved. Chapter 28 Diuretic Drugs Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Diuretic Drugs Drugs that accelerate the rate of urine formation Result in the removal of sodium and water Used in the treatment of hypertension, heart failure (HF), and renal failure Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Sodium In the nephron, where sodium goes, water follows. 60% to 70% of sodium and water is returned to bloodstream by the proximal tubule. 20% to 25% of all sodium is reabsorbed into the bloodstream in the ascending loop of Henle. 5% to 10% is reabsorbed in the distal tubules. 3% is reabsorbed in collecting ducts. If water is not absorbed, it is excreted as urine. Copyright © 2017, Elsevier Inc. All rights reserved.

The Nephron and Diuretic Sites of Action Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question Which location is the area where the highest percentage of sodium and water are resorbed back into the bloodstream? Glomerulus Proximal tubule Ascending loop of Henle Distal tubule Correct answer: B Rationale: The proximal convoluted (twisted) tubule or, more simply, proximal tubule, anatomically follows the glomerulus and returns 60% to 70% of the sodium and water from the filtered fluid back into the bloodstream. Another 20% to 25% of sodium is resorbed into the bloodstream in the ascending loop of Henle. The remaining 5% to 10% of sodium resorption takes place in the distal convoluted tubule, often called simply the distal tubule, which anatomically follows the ascending loop of Henle. The glomerulus does not resorb sodium or water but instead is the point of initial filtration of the blood. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Types of Diuretic Drugs Carbonic anhydrase inhibitors (CAIs) Loop diuretics Osmotic diuretics Potassium-sparing diuretics Thiazide and thiazide-like diuretics Copyright © 2017, Elsevier Inc. All rights reserved.

Carbonic Anhydrase Inhibitors Acetazolamide (Diamox) Most commonly used CAI Copyright © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

Carbonic Anhydrase Inhibitors: Mechanism of Action (Cont.) 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 © 2017, Elsevier Inc. All rights reserved.

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 High-altitude sickness Copyright © 2017, Elsevier Inc. All rights reserved.

Carbonic Anhydrase Inhibitors: Contraindications Known drug allergy Hyponatremia Hypokalemia Severe renal or hepatic dysfunction Adrenal gland insufficiency Cirrhosis Copyright © 2017, Elsevier Inc. All rights reserved.

Carbonic Anhydrase Inhibitors: Adverse Effects Acidosis Hypokalemia Drowsiness Anorexia Paresthesias Hematuria Urticaria Photosensitivity Melena (blood in the stool) Copyright © 2017, Elsevier Inc. All rights reserved.

Carbonic Anhydrase Inhibitors: Interactions Because CAIs can cause hypokalemia, an increase in digoxin toxicity may occur when they are combined with digoxin. Use with corticosteroids may also cause hypokalemia. Increased effects of amphetamines, carbamazepine, cyclosporine, phenytoin, and quinidine with concurrent use of CAIs Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Loop Diuretics bumetanide (Bumex) ethacrynic acid (Edecrin) furosemide (Lasix) torsemide (Demadex) Copyright © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

Loop Diuretics: Drug Effects Potent diuresis and subsequent loss of fluid Decreased fluid volume causes a reduction in Blood pressure Pulmonary vascular resistance Systemic vascular resistance Central venous pressure Left ventricular end-diastolic pressure Potassium and sodium depletion Copyright © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

Loop Diuretics: Adverse Effects (Cont.) Body System Adverse Effects Hematologic Agranulocytosis, neutropenia, thrombocytopenia Metabolic Hypokalemia, hyperglycemia, hyperuricemia Copyright © 2017, Elsevier Inc. All rights reserved.

Loop Diuretics: Interactions Neurotoxic Nephrotoxic Increase serum levels of uric acid, glucose, alanine aminotransferase, and aspartate aminotransferase. Thiazide (metolazone): sequential nephron blockade Nonsteroidal antiinflammatory drugs (NSAIDs) Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Loop Diuretics: Furosemide (Lasix) Most commonly used loop diuretic Uses: pulmonary edema and the edema associated with HF, liver disease, nephrotic syndrome, ascites, hypertension Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Audience Response System 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? lithium (Eskalith) acetaminophen (Tylenol) penicillin theophylline Correct answer: A Rationale: Use of loop diuretics with lithium can increase the risk of lithium toxicity. Drug interactions with loop diuretic therapy can occur with concurrent use of nonsteroidal antiinflammatory drugs (NSAIDs), and vancomycin can cause increased neuro- and ototoxicity when used with loop diuretics. There is no associated risk of drug interaction when taking acetaminophen, penicillin, or theophylline with loop diuretics. 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. Osmotic Diuretics Mannitol (Osmitrol) Most used osmotic diuretic Urea Organic acids Glucose Copyright © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

Osmotic Diuretics: Drug Effects Increases glomerular filtration rate and renal plasma flow; helps to prevent kidney damage during ARF Reduces intracranial pressure or cerebral edema associated with head trauma Reduces excessive intraocular pressure Copyright © 2017, Elsevier Inc. All rights reserved.

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 Copyright © 2017, Elsevier Inc. All rights reserved.

Osmotic Diuretics: Adverse Effects Convulsions Thrombophlebitis Pulmonary congestion Copyright © 2017, Elsevier Inc. All rights reserved.

Osmotic Diuretics: Mannitol (Osmitrol) Intravenous (IV) infusion only May crystallize when exposed to low temperatures Use of a filter is required. Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System 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 administer the infusion slowly. discard the solution and obtain another bag of medication. obtain a filter and then infuse the solution. return the fluid to the IV bag to dissolve the crystals. Correct answer: B Rationale: Even though a filter should always be used with this medication infusion, a solution with crystals present in the bag or tubing should never be infused. The nurse should first discard the solution and then restart the infusion with a new bag, ensuring that there is a filter on the IV line. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Potassium-Sparing Diuretics amiloride (Midamor) spironolactone (Aldactone) triamterene (Dyrenium) Also known as aldosterone-inhibiting diuretics Copyright © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

Potassium-Sparing Diuretics: Indications spironolactone and triamterene Hyperaldosteronism Hypertension Reversing potassium loss caused by potassium-losing drugs Certain cases of HF: prevention of remodeling amiloride Similar as spironolactone and triamterene. but amiloride is less effective in the long term Copyright © 2017, Elsevier Inc. All rights reserved.

Potassium-Sparing Diuretics: Adverse Effects Body System Adverse Effects CNS Dizziness, headache GI Cramps, nausea, vomiting, diarrhea Other Urinary frequency, weakness, hyperkalemia Copyright © 2017, Elsevier Inc. All rights reserved.

Potassium-Sparing Diuretics: Adverse Effects (Cont.) Spironolactone (Aldactone) Gynecomastia Amenorrhea Irregular menses Postmenopausal bleeding Copyright © 2017, Elsevier Inc. All rights reserved.

Potassium-Sparing Diuretics: Interactions Lithium Angiotensin-converting enzyme inhibitors Potassium supplements NSAIDs Copyright © 2017, Elsevier Inc. All rights reserved.

Thiazide and Thiazide-Like Diuretics Thiazide diuretics hydrochlorothiazide (Esidrix, HydroDIURIL) chlorothiazide (Diuril) Thiazide-like diuretics metolazone (Mykrox, Zaroxolyn) chlorthalidone (Hydone, Thalitone) indapamide (Lozol) Copyright © 2017, Elsevier Inc. All rights reserved.

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 © 2017, Elsevier Inc. All rights reserved.

Thiazide and Thiazide-Like Diuretics: Drug Effects Lowered peripheral vascular resistance Depletion of sodium and water (and potassium) Copyright © 2017, Elsevier Inc. All rights reserved.

Thiazide and Thiazide-Like Diuretics (Cont.) Thiazides should not be used if creatinine clearance is less than 30 to 50 mL/min (normal is 125 mL/min). Metolazone remains effective to a creatinine clearance of 10 mL/min. Copyright © 2017, Elsevier Inc. All rights reserved.

Thiazide and Thiazide-Like Diuretics: Indications Hypertension (one of the most prescribed group of drugs for this) Edematous states Idiopathic hypercalciuria Diabetes insipidus HF caused by diastolic dysfunction Adjunct drugs in treatment of edema related to HF, hepatic cirrhosis, or corticosteroid or estrogen therapy Copyright © 2017, Elsevier Inc. All rights reserved.

Thiazide and Thiazide-Like Diuretics: Adverse Effects Body System Adverse Effects CNS Dizziness, headache, blurred vision GI Anorexia, nausea, vomiting, diarrhea Genitourinary Impotence Hematologic Jaundice, leukopenia Copyright © 2017, Elsevier Inc. All rights reserved.

Thiazide and Thiazide-Like Diuretics: Adverse Effects (Cont.) Body System Adverse Effects Integumentary Urticaria, photosensitivity Metabolic Hypokalemia, hyperglycemia, hyperuricemia, hypochloremic alkalosis Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. 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 blood pressure). Assess for disorders that may contraindicate or necessitate cautious use of these drugs. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Instruct patients to take the medication in the morning if possible to avoid interference with sleep patterns. Monitor serum potassium levels during therapy. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) 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 © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Patients taking diuretics along with a digitalis preparation should be taught to monitor for digitalis toxicity. Patients with diabetes mellitus who are taking thiazide or loop diuretics should be told to monitor blood glucose and watch for elevated levels. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) 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 © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Patients who have been ill with nausea, vomiting, or diarrhea should notify their primary care providers 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 © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Instruct patients to notify their primary care providers 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 © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Monitor for adverse effects: Metabolic alkalosis, drowsiness, lethargy, hypokalemia, tachycardia, hypotension, leg cramps, restlessness, decreased mental alertness Monitor for hyperkalemia with potassium-sparing diuretics. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Monitor for therapeutic effects: Reduction of edema Reduction of fluid volume overload Improvement in manifestations of HF Reduction of hypertension Return to normal intraocular pressures Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Case Study A patient with a creatinine clearance of 20 mL/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? Potassium sparing Thiazide Osmotic Loop Correct answer: D Rationale: The loop diuretics provide rapid diuresis because of their rapid onset of action. Loop diuretics are effective for patients with reduced kidney function (creatinine clearance below 25 mL/min). 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. Case Study (Cont.) 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? Aminoglycosides Sulfonamides Macrolides Penicillins Correct answer: B Rationale: The nurse should assess patients receiving furosemide (Lasix) for cross-sensitivity to sulfonamides. Although allergy to sulfonamide antibiotics is listed as a contraindication, analysis of the literature indicates that cross-reaction with the loop diuretics is unlikely to occur. Loop diuretics are commonly given to such patients in clinical practice. The nurse should closely monitor these patients. 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. Case Study (Cont.) 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)? Hypocalcemia Hypophosphatemia Hypokalemia Hypomagnesemia Correct answer: C Rationale: Of all of the adverse effects of furosemide (Lasix) administration, hypokalemia is of serious clinical importance. To prevent hypokalemia, patients often receive potassium supplements along with furosemide. The other electrolyte disturbances listed do not occur as a result of furosemide (Lasix) therapy. 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. Case Study (Cont.) The patient is being discharged home with furosemide (Lasix). When providing discharge teaching, which instruction will the nurse include? 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 lb. Correct answer: A Rationale: Patients taking furosemide (Lasix) should avoid prolonged exposure to the sun because the drug can cause photosensitivity. Although orthostatic hypotension is a possible adverse effect of the medication, patients should not stop taking the medication without consultation with their health care provider. Patients should weigh themselves once a day and report a weight gain or loss of approximately 3 lb. Patients taking furosemide (Lasix) should be encouraged to eat foods rich in potassium. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.