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Diuretics: Mechanism of Action & Types

Nursing Knowledge

Diuretics: Mechanism of Action & Types

Diuretics are a class of medications that are commonly used in clinical practice. They are indicated for a variety of conditions, including hypertension, heart failure, and edema. As a nurse, it is important to have a thorough understanding of diuretics and the mechanisms of action, as well as potential side effects and interactions with other medications.

Last updated: December 17, 2024

What are diuretics?

Diuretics are medications that increase the kidney’s production and output of urine in an effort to lower blood pressure and/or decrease edema. They’re commonly used to treat conditions like hypertension (high blood pressure), heart failure, and edema (fluid buildup).

What are the types of diuretics?

Loop diuretics

Limit reabsorption of Na⁺ and Cl^–, increasing urine production
Work in loop of Henle to remove salt and excess water
Furosemide is commonly used.

Thiazides

Thiazide effects are similar to loop diuretics. They increase renal excretion on Na⁺, Cl^–, K⁺ and H₂O and elevate plasma levels of glucose and uric acid.
Thiazide is not effective when renal blood flow is low.
Thiazide-induced diuresis is less than loop diuretic.
HCTZ is the most commonly prescribed thiazide diuretic.

Potassium-sparing diuretics

Potassium-sparing diuretics cause mild increase in urine output.
Not often used in monotherapy, but can be used with loop diuretics to counteract K⁺ loss from other medications.
Hyperkalemia is an adverse effect which can lead to life-threatening dysrhythmias.
Use spironolactone with caution when taking other medications that also raise K⁺ (ACE inhibitors, ARBs and DRIs).
Removes salt and water without removing excess potassium

Carbonic anhydrase inhibitors

Osmotic diuretic given IV
Most of filtered drug remains in the nephron
Increases osmotic pressure in lumen of the proximal tubule and the loop of Henle
Causes increased water diuresis

Comparison chart of diuretics

A comparison of thiazide, loop diuretics, and potassium-sparing diuretics

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How do diuretics work?

Mechanism of action of loop diuretics

Loop diuretics (e.g., furosemide) reduce Na⁺reabsorption in the loop of Henle.

Mechanism of action of thiazides

Thiazides (e.g., hydrochlorothiazide) inhibit Na⁺, Mg⁺, K⁺, and Cl^– reabsorption in the distal convoluted tubules.

Mechanism of action of potassium-sparing diuretics

Potassium-sparing diuretics (e.g., spironolactone, triamterone) inhibit aldosterone receptors or prevent Na⁺ reabsorption in the distal tubule.

Related videos

Loop Diuretics: MOA and Routes

Potassium-sparing Diuretics

Thiazide Diuretics

Diuretics – NCLEX Review

What is a nephron?

A nephron is a functional unit of the kidney. Each kidney has about 1,000,000 nephrons. Nephrons stretch from the cortex to the medulla of the kidney. Each nephron has three parts:

Tubule (PCT & DCT)
Glomerulus
Bowman’s capsule

What are diuretics used for?

Table: Indications of different types of diuretics

	Thiazide diuretics	Potassium-sparing diuretics		Loop diuretics
Common drugs	Hydrochlorothiazide	Spironolactone	Triamterene	Furosemide
Uses	Hypertension,edema, heart failure	Hypertension, edema, heart failure, acne, hirsutism	Hypertension, edema, heart failure	Hypertension, edema, heart failure

Side effects of diuretics: comparison

Table: Side effects of different types of diuretics

	Thiazide diuretics	Potassium-sparing diuretics		Loop diuretics
Common drugs	Hydrochlorothiazide	Spironolactone	Triamterene	Furosemide
Side effects	Hypokalemia, hyponatremia, photosensitivity	Hyperkalemia, lightheadedness, gynecomastia		Hypokalemia, hyponatremia, hypomagnesemia

Nursing teachings for diuretics

Take medication as directed.
Elderly and fall-risk patients should take any evening doses by early evening.
Educate for fluid intake as ordered by provider.
Monitor for weight changes.
Maintain follow-up visits.

What foods are natural diuretics?

Many foods and beverages have natural diuretic properties, including:

Watermelon
Cucumber
Lemon
Pineapple
Ginger
Parsley
Celery
Berries
Beets
Green tea
Asparagus
Coffee (caffeine)
Grapes
Apple cider vinegar

When to stop diuretics in heart failure

The decision to discontinue diuretics or adjust the dose for clients with heart failure is made by the supervising physician.

Considerations influencing the decision to discontinue diuretics can include the following:

If symptoms of fluid overload or congestion stop (clinical stability)
Risk of hypotension present
Electrolyte imbalances present
Decline in kidney function
Interactions with other medications
Client’s weight drops significantly

RELATED TOPIC:

5 Rights of Medication Administration

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Diuretics: Mechanism of Action & Types

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Diuretics, also called water pills, are a some of the most commonly prescribed medications out there. Find out how they work and what you should to know about them.

Master the topic with a unique study combination of a concise summary paired with video lectures.

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