Potassium-Sparing Diuretics: Managing Hypertension and Heart Failure

Potassium-Sparing Diuretics: An Overview

Diuretics, also called water pills, are drugs that help the kidneys remove excess fluid and sodium from the body through urine. They are commonly prescribed to lower blood pressure, and treat heart failure and liver cirrhosis. There are different types of diuretics, depending on the part of the kidney cells where they act, such as the distal convoluted tubule, loop of Henle, cortical collecting duct, and proximal or distal nephron.

Thiazide Diuretics

Thiazide diuretics such as hydrochlorothiazide (Microzide, others), chlorthalidone (Hygroton), and bendroflumethiazide help the kidneys eliminate extra sodium and water into urine by preventing the reabsorption of sodium. This also results in increased elimination of potassium in the urine. As a result, taking a thiazide diuretic can result in hypokalemia (low blood potassium levels).

Loop Diuretics

Loop diuretics such as furosemide (Lasix), bumetanide (Bumex), torsemide (Soaanz), and ethacrynic acid (Edecrin) remove excess salt and water from the body. These drugs also deplete potassium levels in the body.

Potassium-Sparing Diuretics

Potassium-sparing diuretics work by helping the kidneys clear out extra sodium and water without losing potassium. They have a mechanism different from other types of diuretics. Some drugs in this class, such as spironolactone, are called mineralocorticoids or aldosterone antagonists (aldosterone receptor antagonists block aldosterone receptors). Others, such as amiloride, block sodium channels in the distal tubule and cortical collecting duct.

Because they are weak diuretics, potassium-sparing diuretics are sometimes used with other classes of diuretics.

Potassium-sparing diuretics can have the opposite effect of loop and thiazide diuretics by causing retention of potassium in the body. They can put you at a higher risk of hyperkalemia (too much potassium in the body), especially if you are taking other medications that can cause high potassium levels, such as blood pressure medications like lisinopril, ramipril, and losartan.

Examples of potassium-sparing diuretics include triamterene (Dyrenium), spironolactone (Aldactone), eplerenone (Inspra), and amiloride (Midamor).

Historical Background

Up to the mid-20th century, substances used to increase urine flow included caffeine (a mild diuretic); digitalis (a strong diuretic that was only useful in heart failure patients); mercury (a potentially toxic substance); and certain acidifying agents of questionable utility.

In the mid-1950s, the first synthetic diuretics, acetazolamide and chlorothiazide, were developed. Over time, a greater understanding of the functioning of the kidneys led to the development of loop and potassium-sparing diuretics in the late 1950s and early 1960s.

Importance in Medical Treatment

Most diuretics target receptors in the tubular cells of the kidneys to prevent the reabsorption of sodium and water. They help in maintaining fluid and electrolyte balance in the body by increasing diuresis (increasing the volume of urine).

Diuretics are used to treat edematous medical conditions such as chronic heart failure, which help reduce the workload of the heart. (Edema is fluid buildup in the body). Taking these medicines can relieve symptoms such as swelling, bloating, and shortness of breath. Diuretics are also used to treat non-edematous conditions such as high blood pressure.

Note: Diuretics affect the levels of electrolytes in the body, including potassium. High and low potassium levels as a result of diuretic therapy can increase the risk of serious health complications such as heart rhythm abnormalities and even cardiac arrest.

Types of Potassium-Sparing Diuretics

Spironolactone

Spironolactone (brand names: Aldactone, CaroSpir) is a potassium-sparing diuretic that is used to treat:

Hyperaldosteronism (primary aldosteronism and secondary aldosteronism are conditions in which there is too much aldosterone hormone in the body).
Heart failure.
Hypertension.
Edema (swelling or fluid retention) caused by kidney or liver disease.

Amiloride

Amiloride (brand name Midamor) is used to treat high blood pressure and heart failure in people with low potassium levels or people in whom low potassium levels could cause problems.

Triamterene

Triamterene (brand name Dyrenium) is a potassium-sparing water pill that decreases sodium reabsorption. It is used to treat edema (fluid retention) caused by heart disease, liver disease, and other medical conditions.

Eplerenone

Eplerenone (brand name Inspra) is used alone or with other drugs to treat hypertension.

Save up to 80% on prescriptions!

Medical Uses and Benefits

Potassium-sparing diuretics are used alone or with other medications to treat a range of medical conditions. The mechanism of action for the two main indications is as follows.

Hypertension (High Blood Pressure)

Potassium-sparing diuretics increase the removal of water from the body. This reduces blood volume (the amount of blood flowing in the veins and arteries) and helps to lower blood pressure.

Heart Failure

Potassium-sparing diuretics help the kidneys flush out the excess fluid from the body. The elimination of excess fluid reduces pressure in the blood vessels. As a result, the heart requires less effort to pump blood.

Treatment and Prevention of Hypokalemia

Potassium-sparing diuretics have a diuretic effect without causing potassium loss. They are useful in people who have hypokalemia or are at risk of hypokalemia (low potassium).

In contrast, thiazide and loop diuretics are potassium-wasting diuretics, meaning they result in increased potassium elimination in the urine. This can lead to hypokalemia (low potassium levels in blood). Therefore, clinical practice guidelines are to avoid loop and thiazide-type diuretics in people at risk of low potassium.

Other Uses of Diuretics

Venous stasis (pooling of blood in the legs)
Pulmonary edema (fluid buildup in the lungs)
Ascites (fluid in the abdomen) due to liver cirrhosis
Nephrotic syndrome (a kidney disorder in which excess protein is lost in urine)
Fluid overload due to impaired renal function (kidney disease)
Metabolic acidosis
Hypercalciuria (high calcium levels in urine)
Kidney stones
Hypercalcemia (high blood calcium levels)
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Increased intraocular pressure
Increased intracranial pressure
Elimination of toxic substances from the body through forced diuresis (urination)

Potential Side Effects and Risks

Common Side Effects

Diuretics make you urinate more often (pee more). Other possible side effects of these medicines include:

Stomach pain
Stomach cramps
Gas
Nausea
Vomiting
Diarrhea
Drowsiness
Dizziness
Tiredness
Headache
Heartburn
Muscle cramps
Enlarged or painful breasts in both men and women
Irregular menstrual periods
Abnormal vaginal bleeding, including postmenopausal vaginal bleeding
Erectile dysfunction
Deepening of the voice
Hirsutism (excessive hair growth)

Tell your doctor if these side effects are severe or do not go away in a few days after your body has had a chance to get used to potassium-sparing diuretics.

Serious Adverse Reactions

Seek emergency medical attention if you develop the following serious symptoms:

Muscle weakness
Numbness and tingling in the hands and feet
Dry mouth, excessive thirst, headache, dizziness (signs of dehydration)
Low energy, loss of appetite, yellowing of the eyes or skin, pain in the right upper abdomen (signs of liver injury)
Skin rash, hives, itching (signs of an allergic reaction)
Chest pain
Fast, slow, or irregular heartbeat
Difficulty breathing or swallowing
Decreased urination
Unusual bleeding or bruising, including blood in vomit or blood in stool
Flu-like symptoms (fever, cough, sore throat)
Fainting

Contraindications

Potassium-sparing diuretics may not be safe for people with certain medical conditions. Before starting treatment with these drugs, tell your doctor if you have:

Addison's disease (adrenal insufficiency)
Hyperkalemia (high blood levels of potassium)
Heart disease
Kidney disease
Liver disease
Diabetes
Gout
Kidney stones

Drug Interactions with Other Medications

Interactions between potassium-sparing diuretics and other drugs can affect how the medications work and/or put you at risk of serious adverse effects. Some of the drug interactions of potassium-sparing diuretics include:

Certain antibiotics
Medications used to treat high blood pressure, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs)
Aspirin and other nonsteroidal anti-inflammatory drugs
Other diuretics
Potassium supplements and salt substitutes

Frequently Asked Questions

Is spironolactone potassium-sparing?

Yes, spironolactone is a potassium-sparing diuretic (water pill). It prevents the kidneys from absorbing too much sodium and water while keeping potassium levels from going too low.

Which diuretic drug is potassium-sparing?

Examples of potassium-sparing diuretics include amiloride (Midamor), spironolactone (Aldactone, Carospir), eplerenone (Inspra), and triamterene (Dyrenium).

Is HCTZ potassium-sparing or wasting?

HCTZ (hydrochlorothiazide) is potassium wasting. It is a thiazide-type diuretic and tends to lower potassium levels in the body.

What diuretic does not deplete potassium?

Potassium-sparing diuretics do not deplete potassium. Examples include spironolactone (Aldactone, Carospir), eplerenone (Inspra), amiloride (Midamor), and triamterene (Dyrenium).

Best Practices for Safe Use

Dosing Guidelines and Monitoring

Take your potassium-sparing diuretics exactly as prescribed. Do not change the dose, dosing frequency, or duration of use without your doctor’s approval.
Keep all your laboratory and medical appointments while on diuretic therapy. Your doctor may want to check your blood potassium levels and kidney function periodically.
Do not take salt substitutes if you are on potassium-sparing diuretics. If you have high blood pressure or heart failure, your doctor may recommend a low-sodium diet. One way to achieve this is by taking salt substitutes. However, salt substitutes have a high amount of potassium, and taking them while on potassium-sparing diuretics can put you at risk of hyperkalemia (high potassium).

Education and Awareness

Talk to your health care provider to ensure you understand the adverse effects of potassium-sparing diuretics and when to seek medical care. Also, make sure you know what dietary and lifestyle modifications are necessary while taking these medicines.

Considerations for Special Populations

Before starting treatment with potassium-sparing diuretics, tell your doctor if you are pregnant, might be pregnant, or are planning a pregnancy in the near future. Also, tell your provider if you are breastfeeding.

Importance of Consulting Your Healthcare Providers

Promptly report any changes in your symptoms, health status, or compliance with medicines to your healthcare provider. Taking your medicine as prescribed can lower the risk of side effects and improve the effectiveness of your potassium-sparing diuretic drug.