34.4: Potassium-Sparing Diuretics
By the end of this section, you should be able to:
- 34.4.1 Identify the characteristics of potassium-sparing diuretic drugs used for fluid volume excess and renal system disorders.
- 34.4.2 Explain the indications, actions, adverse reactions, and interactions of potassium-sparing diuretic drugs used for fluid volume excess and renal system disorders.
- 34.4.3 Describe nursing implications of potassium-sparing diuretic drugs used for fluid volume excess and renal system disorders.
- 34.4.4 Explain the client education related to potassium-sparing diuretic drugs used for fluid volume excess and renal system disorders.
Potassium-sparing diuretics increase urinary output by inhibiting sodium reabsorption in the distal tubules and by decreasing potassium and hydrogen ion secretion and blocking the mineral corticoid sites. These drugs are commonly used in combination with other diuretics to modify potassium losses.
Introduction and Use
Potassium-sparing diuretics affect the reabsorption of sodium and the excretion of potassium in the connecting and collecting tubules by inhibiting the sodium transporters and blocking the mineral corticoid receptors. In contrast to the actions of other diuretics, when the potassium-sparing drugs inhibit sodium reabsorption in this area of the nephron, potassium excretion is decreased, thus preserving serum potassium levels.
All potassium-sparing diuretics are used to treat or prevent hypokalemia associated with the use of loop diuretics and thiazide diuretics. The diuretic action of potassium-sparing diuretics is weaker than in other diuretic types, and the onset of action is delayed by as much as 3 days; however, the drugs are often used in combination with more potent diuretics to prevent or treat hypokalemia, heart failure, and hypertension.
Spironolactone is a potassium-sparing diuretic that competes with the aldosterone (mineralocorticoid) receptors in the distal tubule and collecting duct of the nephron. It is approved to treat hypokalemia, primary hyperaldosteronism, heart failure, edema resulting from cirrhosis, and edema resulting from nephrotic syndrome that is resistant to other treatments. Spironolactone is often added as the fourth drug to treat resistant hypertension, which is defined as failure to reach blood pressure target levels when the client is receiving adequate doses of three antihypertensive drugs. In the early landmark Randomized Aldactone Evaluation Study (RALES), spironolactone was found to reduce mortality from all causes by 30% in clients with heart failure (Patibandla et al., 2022) . In 2017, the American Heart Association recommended spironolactone as the treatment of choice in clients with class II–IV heart failure with a potassium level less than 5 mEq/L and creatinine clearance greater than 30 mL/hr (Patibandla et al., 2022). In this client population, spironolactone decreased hospital readmission rates, myocardial fibrosis, hypertrophy of cardiac muscle, and extracellular fluid volume. The drug is used off-label as part of gender-affirming hormone therapy and to treat hirsutism (excessive hair growth in a male growth pattern) and acne.
Amiloride is recommended for the treatment of uncomplicated essential hypertension and chronic heart failure (Almajid & Cassagnol, 2022). Several potential off-label uses for amiloride include treatment of increased urinary output associated with lithium therapy, insulin-induced edema, and multiple myeloma. Triamterene is a potassium-sparing diuretic that also increases the excretion of magnesium. Triamterene is used to treat edema associated with heart failure, nephrotic syndrome, ascites due to cirrhosis, hypertension, and hyperkalemia.
Table 34.5 lists common potassium-sparing diuretics and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
| Spironolactone ( Aldactone ) |
Heart failure:
25–50 mg orally once daily.
Hypertension: 25–100 mg orally once daily or in divided doses. Edema: 100 mg orally in single or divided doses of 25–200 mg daily. Hyperaldosteronism: 100–400 mg daily. |
| Amiloride ( Midamor ) | CHF or hypertension: 5–20 mg orally daily with food. |
| Triamterene ( Dyrenium ) | Edema associated with congestive heart failure, liver cirrhosis, nephrotic syndrome, secondary hyperaldosteronism, steroid use, or idiopathic causes: 100 mg orally twice daily titrated to effect up to 300 mg daily. |
|
Eplerenone
( Inspra ) |
Heart failure post–myocardial infarction:
Initial dose: 25 mg orally once daily, titrated upward to 50 mg once daily; dose may need to be adjusted depending on potassium levels.
Hypertension: 50 mg orally once daily; can be increased to 50 mg twice daily if needed. |
Adverse Effects and Contraindications
Adverse effects related to the diuretic action of these drugs include hyperkalemia, hyponatremia, and hyperuricemia, as well as renal tubular necrosis, glucose intolerance, and metabolic acidosis. Endocrine effects of spironolactone therapy include gynecomastia (enlarged breasts), decreased libido, and other feminizing effects in male clients and menstrual alterations in female clients.
Contraindications include anuria, hyperkalemia, and renal insufficiency. These medications should be used with caution in older adults and individuals who have diabetes or gout.
Table 34.6 is a drug prototype table for potassium-sparing diuretics featuring spironolactone. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
|
Drug Class
Potassium-sparing diuretics Mechanism of Action Opposes the mineralocorticoid receptors that block the action of aldosterone, resulting in decreased reabsorption of sodium and retention of potassium |
Drug Dosage
Heart failure: 25–50 mg orally once daily. Hypertension: 25–100 mg orally once daily or in divided doses. Edema: 100 mg orally in single or divided doses of 25–200 mg daily. Hyperaldosteronism: 100–400 mg daily. |
|
Indications
Heart failure with reduced ejection fraction Resistant hypertension Primary hyperaldosteronism Edema secondary to cirrhosis or nephrotic syndrome Therapeutic Effects Relieves fluid excess Increases urinary output Reduces potassium excretion |
Drug Interactions
Medications that increase serum potassium, including potassium supplements, ACE inhibitors, and angiotensin II receptor blockers (ARBs) Lithium Nonsteroidal anti-inflammatory drugs Digoxin Cholestyramine Acetylsalicylic acid (aspirin) Food Interactions Can be taken with or without food but should be taken consistently with respect to food Potassium salt substitutes Potassium-rich food |
|
Adverse Effects
Hyperkalemia Hyponatremia Hypotension Bradycardia Hepatic failure Worsening renal function Electrolyte abnormalities such as hyponatremia Gynecomastia |
Contraindications
Anuria Hyperkalemia Severe hypovolemia Addison’s disease |
Safety Alert
Potassium-Sparing Diuretics
Clients taking potassium-sparing diuretics are accordingly at risk for hyperkalemia and its associated adverse effects. Hyperkalemia can cause arrhythmias and cardiac arrest if untreated.
(Source: Simon et al., 2023)
Nursing Implications
The nurse should do the following for clients taking potassium-sparing diuretics:
- Assess and monitor the client’s heart rate and blood pressure and perform a physical assessment to auscultate lung sounds and check for the presence of edema.
- Monitor the client’s weight for any significant increases (2 pounds in one day or 5 pounds in 1 week), which could indicate fluid retention.
- Monitor laboratory tests for electrolyte imbalances.
- Monitor the client’s ECG for any changes in cardiac rhythm.
- Assess and monitor for drug and food interactions.
- Provide client teaching regarding the drug and when to call the health care provider. See below for additional teaching guidelines.
Clinical Tip
Dietary Potassium
Clients should be cautioned about consuming salt substitutes, bananas, and other potassium-rich foods when taking potassium-sparing diuretics. Clients often associate “water pills” with the need for additional dietary potassium.
(Source: DailyMed, Spironolactone, 2020)
Client Teaching Guidelines
The client taking a potassium-sparing diuretic should:
- Follow a balanced diet with limited intake of potassium-rich foods to decrease the risk of hyperkalemia.
- Take medications consistently regarding food (take either with or without food).
- Report gynecomastia, menstrual irregularities, and the onset of any additional endocrine alterations.
The client taking a potassium-sparing diuretic should not:
- Use potassium-based salt substitutes.
- Take nonsteroid anti-inflammatory medications without consulting their health care provider because these can increase potassium levels.
FDA Black Box Warning
Potassium-Sparing Diuretics
Spironolactone , a potassium-sparing diuretic that also antagonizes aldosterone receptor sites, may cause the development of several tumor types when administered at high doses that exceed current recommendations.
Amiloride , a potassium-sparing diuretic, may cause hyperkalemia, either alone or when combined with hydrochlorothiazide and ACE inhibitors.
Triamterene , a potassium-sparing diuretic, may cause hyperkalemia, either alone or when combined with hydrochlorothiazide. This is more likely to develop in clients with renal impairment and diabetes.