Chapter 28 Diuretic Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc

Chapter 28

Diuretic Drugs

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

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

Diuretic Drugs

2Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

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

Sodium


The Nephron and Diuretic Sites of Action


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


Carbonic anhydrase inhibitors Loop diuretics Osmotic diuretics Potassium-sparing diuretics Thiazide and thiazide-like diuretics

Types of Diuretic Drugs


acetazolamide (Diamox) Most commonly used CAI

Carbonic Anhydrase Inhibitors (CAIs)


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

Carbonic Anhydrase Inhibitors: Mechanism of Action


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

Carbonic Anhydrase Inhibitors: Mechanism of Action (cont’d)


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

Carbonic Anhydrase Inhibitors: Indications


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

Carbonic Anhydrase Inhibitors: Indications (cont’d)


Carbonic Anhydrase Inhibitors: Adverse Effects

Metabolic acidosis Anorexia Hematuria Photosensitivity Melena

Hypokalemia Drowsiness Paresthesias Urticaria Glycosuria in diabetic

patients


bumetanide (Bumex) ethacrynic acid (Edecrin) furosemide (Lasix) torsemide (Demadex)

Loop Diuretics


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

Loop Diuretics: Mechanism of Action


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

Loop Diuretics: Drug Effects


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

Loop Diuretics: Indications


Loop Diuretics: Adverse Effects

Body System Adverse EffectsCentral nervous system (CNS) Dizziness, headache,

tinnitus, blurred vision

Gastrointestinal (GI) Nausea, vomiting, diarrhea

Integumentary Stevens-Johnson

syndrome (torsemide)


Body System Adverse Effects

Hematologic Agranulocytosis, neutropenia, thrombocytopenia

Metabolic Hypokalemia, hyperglycemia,hyperuricemia

Loop Diuretics: Adverse Effects (cont’d)



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


mannitol (Osmitrol) Most used osmotic diuretic

Urea Organic acids Glucose

Osmotic Diuretics


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

Osmotic Diuretics: Mechanism of Action


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

Osmotic Diuretics: Drug Effects


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

Osmotic Diuretics: Indications


Convulsions Thrombophlebitis Pulmonary congestion Also headaches, chest pains, tachycardia,

blurred vision, chills, and fever

Osmotic Diuretics: Adverse Effects


Intravenous infusion only May crystallize when exposed to low

temperatures Use of a filter is required

Osmotic Diuretics: Mannitol (Osmitrol)



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.


amiloride (Midamor) spironolactone (Aldactone) triamterene (Dyrenium)

Also known as aldosterone-inhibiting diuretics

Potassium-Sparing Diuretics


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

Potassium-Sparing Diuretics: Mechanism of Action


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

Potassium-Sparing Diuretics: Drug Effects


spironolactone and triamterene Hyperaldosteronism Hypertension Reversing potassium loss caused by potassium-

losing drugs Certain cases of HF

amiloride Treatment of HF

Potassium-Sparing Diuretics: Indications



CNS Dizziness, headache

GI Cramps, nausea, vomiting, diarrhea

Other Urinary frequency,weakness, hyperkalemia

Potassium-Sparing Diuretics: Adverse Effects


spironolactone (Aldactone) Gynecomastia Amenorrhea Irregular menses Postmenopausal bleeding

Potassium-Sparing Diuretics: Adverse Effects (cont’d)


Thiazide diuretics hydrochlorothiazide (Esidrix, HydroDIURIL) chlorothiazide (Diuril)

Thiazide-like diuretics metolazone (Mykrox, Zaroxolyn) chlorthalidone (Hydone, Thalitone) indapamide (Lozol)

Thiazide and Thiazide-like Diuretics


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

Thiazide and Thiazide-like Diuretics: Mechanism of Action


Lowered peripheral vascular resistance Depletion of sodium and water (and potassium)

Thiazide and Thiazide-like Diuretics: Drug Effects


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

Thiazide and Thiazide-like Diuretics (cont’d)


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

Thiazide and Thiazide-like Diuretics: Indications

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 37


CNS Dizziness, headache, blurred vision

GI Anorexia, nausea, vomiting, diarrhea

GU Impotence

Hematologic Jaundice, leukopenia

Thiazide and Thiazide-like Diuretics: Adverse Effects


Body System Adverse EffectsIntegumentary Urticaria,

photosensitivity

Metabolic Hypokalemia, hyperglycemia, hyperuricemia,

hypochloremic alkalosis

Thiazide and Thiazide-like Diuretics: Adverse Effects (cont’d)


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

Nursing Implications


Instruct patients to take the medication in the morning if possible to avoid interference with sleep patterns

Monitor serum potassium levels during therapy

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



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



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



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



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



Monitor for adverse effects Metabolic alkalosis, drowsiness, lethargy,

hypokalemia, tachycardia, hypotension, leg cramps, restlessness, decreased mental alertness

Monitor for hyperkalemia with potassium-sparing diuretics



Monitor for therapeutic effects Reduction of edema Reduction of fluid volume overload Improvement in manifestations of heart failure Reduction of hypertension Return to normal intraocular pressures



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?

A.Potassium-sparingB.ThiazideC.OsmoticD.Loop


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.AminoglycosidesB.SulfonamidesC.MacrolidesD.Penicillins



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.HypocalcemiaB.HypophosphatemiaC.HypokalemiaD.Hypomagnesemia



The patient is being discharged home with furosemide (Lasix). When providing discharge teaching, which instruction will the nurse include?

A. Avoid prolonged exposure to the sun.B. Avoid foods high in potassium content.C. Stop taking the medication if you feel dizzy.D. Weigh yourself once a week and report a gain or

loss of more than 1 pound.


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Chapter 28 Diuretic Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc