Diuretics are drugs that primarily increase the excretion of sodium. To some extent, they also increase the volume of urine produced by the kidneys.

By blocking the absorptive capacity of cells lining the renal tubules for sodium, intravascular volume and the eventual leaking of fluid from capillaries is reduced and prevented.

It is used in the management of diseases like glaucoma, hypertension, and edema in heart failure, liver failure, and renal diseases.

Table of Common Drugs and Generic Names


Here is a table of commonly encountered diuretic agents, their generic names, and brand names:

Classification Generic Name Brand Name
Thiazide diuretics
Thiazide diuretics bendroflumethiazide Naturetin
chlorothiazide Diuril
hydrochlorothiazide HydroDIURIL
hydroflumethiazide Saluron
methyclothiazide Enduron
Thiazide-like diuretics chlorthalidone Hygroton
indapamide Lozol
metolazone Mykrox, Zaroxolyn
Loop diuretics bumetanide Bumex
ethacrynic acid Edecrin
furosemide Lasix
torsemide Demadex
Carbonic Anhydrase Inhibitors acetazolamide Diamox
methazolamide Glauctabs, MZM, Neptazane
Potassium-sparing Diuretics amiloride Midamor
spironolactone Aldactone
triamterene Dyrenium
Osmotic Diuretics mannitol Osmitrol

Disease Spotlight: Edema, Hypertension, and Glaucoma


Edema is the accumulation of fluids in the interstitial spaces. It can be typically seen in patients with heart failure (HF), cirrhosis and other liver diseases, and renal diseases.

  • Edema in HF is caused by activation of the renin-angiotensin system due to an inefficient pumping activity of the heart. As a result, blood volume increases and sodium is retained.
  • Cirrhosis and other liver diseases present with edema because of two reasons: 1) reduced plasma protein production leading to decreased oncotic pressure (pressure that holds the fluid in); and 2) portal system obstruction due to hepatic vessel congestion.
  • Edema in renal diseases is because of damaged basement membrane which makes it possible for plasma proteins to be lost into urine.

Hypertension is persistent higher-than-normal blood pressure and is primarily idiopathic (no known cause). When not acted upon promptly, this can lead to multiple organ failure and severe cardiovascular complications. Diuretic agents are used in management of hypertension to reduce blood pressure by decreasing circulating fluid volume and sodium.

Glaucoma is an eye disease that is characterized by increased intraocular pressure (IOP), which is the pressure inside the eyes. When not acted upon promptly, high IOP can damage optic nerve and cause irreversible blindness. Diuretic agents are used in the management of glaucoma by enhancing the osmotic pull to effectively remove some fluid in the eye, decreasing the IOP. 

Thiazide and Thiazide-like Diuretics


Description

  • Thiazide diuretics belong to a chemical class of drugs called sulfonamides. Thiazide-like diuretics have different chemical structure but work in the same mechanism as that of thiazide diuretics.
  • This is among the most commonly used class of diuretics.

Therapeutic Action

  • It causes active pumping out of chloride from the cells lining the ascending limb of Loop of Henle and distal tubule by blocking the chloride pump. Since sodium passively moves with chloride to maintain electrical neutrality, both sodium and chloride are excreted in the urine.

Indication

  • Considered to be a milder form of diuretics compared to loop diuretics.
  • First-line drugs for management of essential hypertension

Children

  • Has established pediatric dosing guidelines used for the treatment of edema in heart defects and hepatorenal diseases; control of hypertension in children.
  • Effect of diuretics may be abrupt in children because of their rapid metabolism so caution is exercised by careful monitoring of serum electrolyte changes and for evidence of fluid volume changes.

Adults

  • Are more likely to use diuretics on long-term basis and should be educated on warning signs of fluid volume changes that need prompt medical attention.
  • They should be instructed to weigh themselves daily to monitor for fluid retention or sudden fluid loss.
  • Conditions that may aggravate fluid loss like vomiting, diarrhea, and profuse sweating should be emphasized to them because these may change the need for diuretics.
  • Use of diuretics to influence fluid shifts in pregnant patients is not appropriate. However, it should not be stopped if indicated for a specific medical cause provided that they are made aware of the possible effects to the fetus. Lactating women should switch to an alternative method of feeding as this drug may have potential effect to the baby.

Older adults

  • Have medical conditions where thiazide diuretics and thiazide-like diuretics are usually indicated.
  • The possibility of older adult patients having renal and hepatic impairments requires health care team to be cautious of the use of this drug.
  • The lowest dose possible is started initially and it is titrated slowly based on patient’s response.
  • Frequent monitoring of serum electrolytes, activity level, and dietary intake is a must.

Pharmacokinetics

Route Onset Peak Duration
Oral 2 h 4-6 h 6-12 h
T1/2: 5.6 – 14 h
Metabolism: liver
Excretion: urine

Contraindications and Cautions

  • Allergy to loop diuretics. Prevent severe hypersensitivity reactions.
  • Fluid and electrolyte imbalances. Can be potentiated by the changes in fluid and electrolyte levels caused by diuretics.
  • Severe renal failure, anuria. May prevent diuretics from working; can precipitate crisis stage due to blood flow changes brought about by diuretics.
  • Systemic lupus erythematosus (SLE).  Can precipitate renal failure because the disease already causes changes in glomerular filtration.
  • Glucose tolerance abnormalities and diabetes mellitus. Worsened by glucose-elevating effect of some diuretics
  • Gout. Already reflects abnormality in tubular reabsorption and secretion.
  • Liver disease. Could interfere with drug metabolism and lead to drug toxicity.
  • Bipolar disorder. Can be exacerbated by calcium changes brought about by the use of this drug.
  • Pregnancy, lactation. Can cause potential adverse effects to the fetus and baby. Routine use of this drug in pregnancy is not appropriate and should be used only when there is underlying pathological conditions. For lactating women, an alternative method of feeding should be instituted.

Adverse Effects

  • CNS: weakness
  • CV: hypotension, arrhythmias
  • GI: GI upset
  • GU: hypokalemia (can precipitate hyperglycemia), hypercalcemia, hyperuremia, slightly-alkalinized urine (can lead to bladder infections)

Interactions

  • Cholestyramine or colestipol: decreased absorption of diuretics; must be taken separated by at least 2 hours.
  • Digoxin: increased risk for digoxin toxicity because of changes in serum potassium levels
  • Quinidine: increased risk for quinidine toxicity
  • Antidiabetic agents: decreased effectivity of antidiabetics
  • Lithium: increased risk for lithium toxicity

Loop Diuretics


Description

  • This type of diuretics exerts its main effect on the loop of Henle. Hence, so named.
  • Referred to as high-ceiling diuretics because they are capable of causing greater degree of diuresis compared to other types.

Therapeutic Action

  • Blocks the action of chloride pump in the ascending limb of the loop of Henle, where 30% of sodium is normally reabsorbed. This causes decreased reabsorption of chloride and sodium.
  • Exerts the same effect on the descending limb of loop of Henle and distal tubule causing sodium-rich urine.

Indications

  • Indicated for treatment of acute HF, acute pulmonary edema, and edema associated with HF or with renal or liver disease, and hypertension.
  • Drug of choice when rapid and extensive diuresis is needed. It can produce a fluid loss up to 20 pounds per day.
  • Proven to be effective even with the presence of acid-base disturbances, renal failure, electrolyte imbalances, and nitrogen retention.
  • Also used in the treatment of pulmonary edema but its effect only influences the blood that reaches the nephrons.
  • Ethacrynic acid is used less frequently in the clinical setting because newer drugs are more potent and reliable.

Children

  • Furosemide is used when a stronger diuretic is needed but dose should not be more than 6 mg/kg/d.
  • Ethacrynic acid is used in oral form in some situations but not in infants.
  • Bumetanide is generally not recommended for children but is indicated when the child is taking other ototoxic drugs (e.g. antibiotics). It causes less hypokalemia and makes it ideal for children taking digoxin at the same time.

Adults

  • Are more likely to use diuretics on long-term basis and should be educated on warning signs of fluid volume changes that need prompt medical attention.
  • They should be instructed to weigh themselves daily to monitor for fluid retention or sudden fluid loss.
  • Conditions that may aggravate fluid loss like vomiting, diarrhea, and profuse sweating should be emphasized to them because these may change the need for diuretics.

Pregnant women

  • Use of diuretics to influence fluid shifts in pregnant patients is not appropriate. However, it should not be stopped if indicated for a specific medical cause provided that they are made aware of the possible effects to the fetus.
  • Lactating women should switch to an alternative method of feeding as this drug may have potential effect to the baby.

Older adults

  • Have medical conditions where thiazide diuretics and thiazide-like diuretics are usually indicated.
  • The possibility of older adult patients having renal and hepatic impairments requires health care team to be cautious of the use of this drug.
  • The lowest dose possible is started initially and it is titrated slowly based on patient’s response.
  • Frequent monitoring of serum electrolytes, activity level, and dietary intake is a must.

Pharmacokinetics

Route Onset Peak Duration
Oral 60 min 60-120 min 6-8 h
IV, IM 5 min 30 min 2 h
T1/2: 120 min
Metabolism: liver
Excretion: urine

Contraindications and Cautions

  • Allergy to thiazides and sulfonamides. Prevent severe hypersensitivity reactions.
  • Electrolyte depletion. Can be potentiated by the changes in fluid and electrolyte levels caused by diuretics.
  • Severe renal failure, anuria. Exacerbated by the effects of the drug.
  • Systemic lupus erythematosus (SLE).  Can precipitate renal failure because the disease already causes changes in glomerular filtration.
  • Glucose tolerance abnormalities and diabetes mellitus. Worsened by glucose-elevating effect of some diuretics
  • Gout. Already reflects abnormality in tubular reabsorption and secretion.
  • Hepatic coma. Exacerbated by fluid shifts associated with drug use.
  • Pregnancy, lactation. Can cause potential adverse effects to the fetus and baby. Routine use of this drug in pregnancy is not appropriate and should be used only when there is underlying pathological conditions. For lactating women, an alternative method of feeding should be instituted.

Adverse Effects

  • CNS: dizziness
  • CV: hypotension
  • GI: GI upset
  • GU: hypokalemia (can precipitate hyperglycemia), increased bicarbonate excretion (can lead to alkalosis), hypocalcemia and tetany
  • EENT: ototoxicity, reversible loss of hearing

Interactions

  • Aminoglycosides or cisplatin: increased ototoxicity effect of loop diuretics
  • Anticoagulants: increased anticoagulation effects
  • Indomethacin, ibuprofen, salicylates and other NSAIDs: decreased antihypertensive effects and loss of sodium

Carbonic Anhydrase Inhibitors


Description

  • Relatively mild diuretics.

Therapeutic Action

  • Inhibits the action of the enzyme carbonic anhydrase, the catalyst for the formation of sodium bicarbonate stored as alkaline reserve in the renal tubules and is important for the excretion of hydrogen.
  • It slows down the movement of hydrogen ions which leads to greater amount of sodium and bicarbonate lost in the urine.

Indications

  • Most often used for the treatment of glaucoma. Inhibition of carbonic anhydrase results in decreased secretion of aqueous humor of the eyes.
  • Also used as adjunct to other diuretics when more intense diuresis is needed.

Children

  • Not indicated for children

Adults

  • Are more likely to use diuretics on long-term basis and should be educated on warning signs of fluid volume changes that need prompt medical attention.
  • They should be instructed to weigh themselves daily to monitor for fluid retention or sudden fluid loss.
  • Conditions that may aggravate fluid loss like vomiting, diarrhea, and profuse sweating should be emphasized to them because these may change the need for diuretics.

Pregnant women

  • Use of diuretics to influence fluid shifts in pregnant patients is not appropriate. However, it should not be stopped if indicated for a specific medical cause provided that they are made aware of the possible effects to the fetus.
  • Lactating women should switch to an alternative method of feeding as this drug may have potential effect to the baby.

Older adults 

  • Have medical conditions where thiazide diuretics and thiazide-like diuretics are usually indicated.
  • The possibility of older adult patients having renal and hepatic impairments requires health care team to be cautious of the use of this drug.
  • The lowest dose possible is started initially and it is titrated slowly based on patient’s response.
  • Frequent monitoring of serum electrolytes, activity level, and dietary intake is a must.

Pharmacokinetics

Route Onset Peak Duration
Oral 1 h 2-4 h 6-12 h
Sustained-release oral 2 h 8-12 h 18-24 h
IV 1-2 min 15-18 min 4-5 h
T1/2:  5-6 h
Metabolism: N/A
Excretion: urine (unchanged)

Contraindications and Cautions

  • Allergy to carbonic anhydrase inhibitors, thiazides, antibacterial sulfonamides. Prevent severe hypersensitivity reactions.
  • Chronic noncongestive angle-closure glaucoma. Not effectively treated by this drug.
  • Fluid and electrolyte imbalance, renal or hepatic disease, adrenocortical insufficiency, respiratory acidosis, chronic obstructive pulmonary disease (COPD). Could be exacerbated by fluid and electrolyte changes caused by these drugs.
  • Pregnancy, lactation. Can cause potential adverse effects to the fetus and baby. Routine use of this drug in pregnancy is not appropriate and should be used only when there is underlying pathological conditions. For lactating women, an alternative method of feeding should be instituted.

Adverse Effects

  • CNS: paresthesia, confusion, drowsiness
  • CV: hypotension
  • GU: hypokalemia (can precipitate hyperglycemia), increased loss of bicarbonate (can lead to metabolic acidosis)

Interactions

  • Salicylate, lithium: increased excretion of these drugs

Potassium-Sparing Diuretics


Description

  • Less powerful than loop diuretics but they retain potassium instead of wasting it.
  • Typically used for patients who have high risk for hypokalemia associated with diuretic use.

Therapeutic Action

  • This type of diuretics causes a loss of sodium while promoting the retention of potassium.
  • Spironolactone acts as aldosterone antagonist which blocks the action of aldosterone in the distal tubule. On the other hand, amiloride and triamterene block potassium secretion through the tubule.

Indications

  • This is often used as adjuncts with thiazide or loop diuretics or in patients who are especially at risk if hypokalemia develops.
  • Spironolactone is the drug of choice for treating hyperaldosteronism typically seen in patients with liver cirrhosis and nephrotic syndrome.

Children 

  • Spironolactone is the only potassium-sparing diuretic recommended for children.

Adults

  • Instruct to avoid potassium-rich foods (e.g. avocados, bananas, broccoli, tomatoes, and dried fruits) and to have regular monitoring of serum potassium levels.

Pregnant Women

  • Use of diuretics to influence fluid shifts in pregnant patients is not appropriate. However, it should not be stopped if indicated for a specific medical cause provided that they are made aware of the possible effects to the fetus.
  • Lactating women should switch to an alternative method of feeding as this drug may have potential effect to the baby.

Older adults

  • Have medical conditions where thiazide diuretics and thiazide-like diuretics are usually indicated.
  • The possibility of older adult patients having renal and hepatic impairments requires health care team to be cautious of the use of this drug.
  • The lowest dose possible is started initially and it is titrated slowly based on patient’s response. Frequent monitoring of serum electrolytes, activity level, and dietary intake is a must.

Pharmacokinetics

Route Onset Peak Duration
Oral 24-48 h 48-72 h 48-72 h
T1/2:  20 h
Metabolism: liver
Excretion: urine (unchanged)

Contraindications and Cautions

  • Allergy to potassium-sparing diuretics. Prevent severe hypersensitivity reactions.
  • Hyperkalemia, renal disease, anuria. Exacerbated by the effects of the drug.
  • Pregnancy, lactation. Can cause potential adverse effects to the fetus and baby. Routine use of this drug in pregnancy is not appropriate and should be used only when there is underlying pathological conditions. For lactating women, an alternative method of feeding should be instituted.

Adverse Effects

  • CNS: lethargy, confusion, ataxia
  • CV: arrhythmias
  • Musculoskeletal: muscle cramps
  • GU: hyperkalemia, increased loss of bicarbonate (can lead to metabolic acidosis)
  • Associated with various androgen effects such as hirsutism, gynecomastia, deepening of the voice, and irregular menses.

Interactions

  • Salicylates: decreased diuretic effect

Osmotic Diuretics


Description

  • This type of diuretic exerts their therapeutic effect by pulling water into the renal tubule without loss of sodium.
  • Only one osmotic diuretic is currently available, mannitol (Osmitrol).

Therapeutic Action

  • Mannitol is a sugar that is not well reabsorbed by the tubules and it acts to pull large amounts of fluid into the urine due to the osmotic pull exerted by large sugar molecule.
  • This also pulls fluid into the vascular system from extravascular spaces like aqueous humor.

Indications

  • Mannitol is usually used in acute situations when it is necessary to decrease IOP before eye surgery or during acute attacks of glaucoma.
  • Diuretic of choice in cases of increased cranial pressure or acute renal failure due to shock, drug overdose, or trauma.
  • Also available as an irrigant in transurethral prostatic resection and other transurethral procedures.

Children

  • Not indicated for children

Adults

  • Conditions that may aggravate fluid loss like vomiting, diarrhea, and profuse sweating should be emphasized to them because these may change the need for diuretics.

Pregnant women

  • Use of diuretics to influence fluid shifts in pregnant patients is not appropriate. However, it should not be stopped if indicated for a specific medical cause provided that they are made aware of the possible effects to the fetus.
  • Lactating women should switch to an alternative method of feeding as this drug may have potential effect to the baby.

Older adults

  • Have medical conditions where thiazide diuretics and thiazide-like diuretics are usually indicated.
  • The possibility of older adult patients having renal and hepatic impairments requires health care team to be cautious of the use of this drug.
  • The lowest dose possible is started initially and it is titrated slowly based on patient’s response. Frequent monitoring of serum electrolytes, activity level, and dietary intake is a must.

Pharmacokinetics

Route Onset Peak Duration
IV 30-60 min 1 h 6-8 h
Irrigant Rapid Rapid Short
T1/2:  15-100 min
Metabolism: N/A
Excretion: urine (unchanged)

Contraindications and Cautions

  • Renal disease, anuria, pulmonary congestion, intracranial bleeding, dehydration, HF. Exacerbated by large shifts in fluid related to drug use.
  • Pregnancy, lactation. Can cause potential adverse effects to the fetus and baby. Routine use of this drug in pregnancy is not appropriate and should be used only when there is underlying pathological conditions. For lactating women, an alternative method of feeding should be instituted.

Adverse Effects

  • CNS: light-headedness, confusion, headache
  • CV: hypotension, cardiac decompensation, shock
  • GI: nausea, vomiting
  • GU: fluid and electrolyte imbalance
  • Most common and potentially dangerous adverse effect related to an osmotic diuretic is the sudden drop in fluid levels.

Nursing Considerations for Diuretic Drugs


Here are important nursing considerations when administering this drug:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned cautions and contraindications (e.g. drug allergies, fluid and electrolyte disturbances, hepatorenal diseases, glucose tolerance abnormalities, etc.) to prevent any untoward complications.
  • Perform a thorough physical assessment to establish baseline data before drug therapy begins, to determine effectiveness of therapy, and to evaluate for occurrence of any adverse effects associated with drug therapy.
  • Inspect skin (note presence of edema and status of skin turgor) to determine hydration status and have a baseline data for effectiveness of drug therapy.
  • Assess cardiopulmonary status (blood pressure, pulse rate, heart and lung sounds, etc.) to evaluate fluid movement and state of hydration. It is also to monitor the effects on the heart and lungs.
  • Obtain an accurate body weight to provide baseline to monitor fluid balance.
  • Monitor intake and output and voiding patterns to evaluate fluid balance and renal function.
  • Evaluate liver status to determine potential problems in drug metabolism.
  • Monitor the results of laboratory tests (e.g. serum electrolyte levels especially potassium and calcium, uric acid and glucose levels, etc.) to determine drug’s effect.
  • Monitor liver and renal function tests to identify need for possible dose adjustment and toxic effects.

Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of this drug for therapy:

  • Impaired urinary elimination related to drug effect
  • Imbalanced nutrition: less than body requirements related to GI upset and metabolic changes
  • Risk for deficient fluid volume related to increase fluid volume excretion
  • Risk for injury related to changes in fluid volume and electrolyte balance

Implementation with Rationale

These are vital nursing interventions done in patients who are taking diuretics:

  • Administer drug with food or milk if GI upset is a problem to buffer drug effect on the stomach lining.
  • Administer intravenous diuretics slowly to prevent severe changes in fluid and electrolytes.
  • Administer oral form early in the day to prevent increased urination during sleep hours.
  • Monitor patient response to drugs through vital signs, weight, serum electrolytes and hydration to evaluate effectiveness of drug therapy.
  • Assess skin condition to determine presence of fluid volume deficit or retention.
  • Provide comfort measures (e.g. skin care, nutrition referral, etc.) to help patient tolerate drug effects.
  • Provide safety measures (e.g. adequate lighting, raised side rails, etc.) to prevent injuries.
  • Educate client on drug therapy to promote compliance.

Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug therapy:

  • Monitor patient response to therapy (e.g. weight, urinary output, edema changes,  blood pressure).
  • Monitor for adverse effects (e.g. electrolyte imbalance, hyperglycemia, hyperuricemia, acid-base disturbances, etc).
  • Evaluate patient understanding on drug therapy by asking patient to name the drug, its indication, and adverse effects to watch for.
  • Monitor patient compliance to drug therapy.

Practice Quiz: Diuretic Agents


Quiz time! Take our 5-item quiz about diuretic agents!

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Questions


1. Most diuretics’ effect in the body is __________.

A. loss of sodium
B. loss of potassium
C. loss of calcium
D. retention of potassium

2. What is the only potassium-sparing diuretics that can be used in children?

A. Furosemide
B. Spironolactone
C. Amiloride
D. Triamterene

3. A patient receiving diuretics should alert the nurse if she feels the following:

A. insomnia
B. low-grade fever
C. muscle weakness
D. all of the above

4. What is the first loop diuretic introduced?

A. Furosemide
B. Bumetanide
C. Torsemide
D. Ethacrynic acid

5. A patient admitted for cerebral swelling complained of feeling light-headed and nauseous while receiving mannitol. What should the nurse do?

A. Document, withdraw, and notify doctor.
B. Decrease mannitol flow.
C. Provide comfort measures.
D. Increase mannitol flow.

Answers and Rationale


1. Answer: A. loss of sodium.

Most diuretics prevent cells lining the renal tubules from reabsorbing an excessive proportion of the sodium ions in the glomerular filtrate.

2. Answer: B. Spironolactone.

Potassium-sparing diuretics include spironolactone, amiloride, and triamterene. Both amiloride and triamterene are not for use in children. Use of spironolactone in children would require careful monitoring of electrolytes.

3. Answer: C. muscle weakness.

This is a sign of hypokalemia and would require prompt intervention. Other signs and symptoms of hypokalemia include arrhythmia and muscle cramps.

4. Answer: A. Furosemide

  • Furosemide was the first loop diuretic to be approved in the United States (1966) and is still widely used today.
  • Ethacrynic acid was the second loop diuretic to be approved for use in the United States (1967), but is now rarely used.
  • Bumetanide is a potent loop diuretic that was approved for use in the United States in 1983 and continues to be used for the treatment of edema.
  • Torsemide was approved for use in edema in the United States in 1993 and is still in common use used for both edema and hypertension.

5. Answer: A. Document, withdraw, and notify doctor.

A sudden drop in fluid level is one of the most potentially fatal adverse effects of mannitol. Manifestations include hypotension, lightheadedness, nausea, and confusion.

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