Name of the Potassium sparing Diuretic agent Drugs
- Spironolactone
- Eplerenone
- Amiloride
- Triamterene
1.Spironolactone
| Spironolactone |
| Availability Tablets: 25 mg, 50 mg, 100 mg |
| Indications and dosages ➣ Edema caused by heart failure, hepatic cirrhosis, or nephrotic syndrome Adults: As sole diuretic, initially 100 mg/day P.O. (range of 25 to 200 mg) in single or divided doses, continued for 5 or more days and then adjusted to optimal therapeutic level Children: 1 to 3 mg/kg/day P.O. as a single dose or in divided doses ➣ Essential hypertension Adults: Initially, 50 to 100 mg/day P.O. as a single dose or in divided doses, continued for at least 2 weeks Children: 1 to 2 mg/kg P.O. b.i.d. ➣ Hypokalemia Adults: 25 to 100 mg/day P.O. ➣ Diagnosis and treatment of primary hyperaldosteronism Adults: For diagnosis, 400 mg/day P.O. for 4 days in short test or for 3 to 4 weeks in long test. Resolution of hypokalemia and hypertension confirm diagnosis of primary hyperaldosteronism. Dosages of 100 to 400 mg/day P.O. may be used as a bridge to surgical therapy; in patients unsuitable for this therapy, lowest effective dosage may be used for long-term maintenance. |
Mechanism of Action
Aldosterone antagonist with diuretic and antihypertensive effects; competitive binding of receptors at aldosterone-dependent Na-K exchange site in distal tubules results in increased excretion of Na+, Cl-, and water and retention of K+ and H+
Increases testosterone clearance and estradiol production; blocks conversion of potent androgens to weaker ones in peripheral tissues
Pharmacokinetics
- Bioavailability: 73% (tablet)
- Protein bound: 90%
- Metabolized by the liver and kidneys
- Half-life (tablet): 1.3-1.4 hr (parent drug); 16.5 hr (canrenone); 13.8 hr (7-α-[thiomethyl] spirolactone [TMS]); 15 hr (6-ß-hydroxy-7-α-[thiomethyl] spirolactone [HTMS])
- Half-life (PO suspension): 1-2 hr (parent drug); 10-35 hr (canrenone, 7-α-[thiomethyl] spirolactone [TMS], 6-ß-hydroxy-7-α-[thiomethyl] spirolactone [HTMS])
- Excretion (tablet): Urine (47-57%); feces (35-41%)
- Excretion (PO suspension): Urine
Administration
- Give single daily dose with breakfast. If two daily doses are prescribed, give second dose with food in mid-afternoon
Contraindications
- Anuria, acute renal insufficiency, significant impairment of renal excretory function
- Hyperkalemia
Precautions :
- Hepatic dysfunction, diabetes mellitus, fluid and electrolyte imbalances, severe heart failure
- Concurrent use of other potassiumsparing diuretics, such as amiloride and triamterene (avoid use)
- Concurrent use of potassium supplements (avoid use with serum potassium level greater than 3.5 mEq/L)
- Concurrent use of ACE inhibitors and nonsteroidal anti-inflammatory drugs (NSAIDs) (use with extreme caution)
- concurrent use of lithium (generally avoid use)
- Elderly or debilitated patients
- Pregnant or breastfeeding patients
- Children (safety not established).
Adverse reactions
- CNS: headache, drowsiness, lethargy, ataxia, confusion
- GI: vomiting, diarrhea, cramping, gastritis, GI ulcers, GI bleeding
- GU: gynecomastia, irregular menses or amenorrhea, postmenopausal bleeding, erectile dysfunction, breast cancer Hematologic: agranulocytosis
- Metabolic: hyponatremia, hyperchloremic metabolic acidosis, hyperkalemia
- Skin: rash, pruritus, hirsutism, drug rash with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson Syndrome, toxic epidermal necrolysis
- Other: deepening of voice, drug fever, hypersensitivity (including vasculitis, anaphylactic reactions)
Patient monitoring
- Monitor electrolyte levels (especially potassium), particularly in patients with severe heart failure. Watch for signs and symptoms of imbalances and metabolic acidosis. Interrupt or discontinue treatment for serum potassium level greater than 5 mEq/L or serum creatinine greater than 4 mg/dl.
- Monitor weight and fluid intake and output. Stay alert for indications of fluid imbalance.
- Monitor CBC with white cell differential.
Patient teaching
- Tell patient to take daily dose with breakfast. If two daily doses are prescribed, advise him to take second dose with food in mid-afternoon.
- Advise patient to restrict intake of high-potassium foods and to avoid licorice and salt substitutes containing potassium.
- Tell male patient drug may cause breast enlargement.
- Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.
Nursing Considerations
- Be aware that for children or patients who have trouble swallowing, pharmacist may crush spironolactone tablets, mix with flavored syrup, and dispense as a suspension. It’s stable 1 month when refrigerated.
- In diagnosing primary aldosteronism, test is considered positive if patient’s serum potassium level rises when spironolactone is given and falls when it’s discontinued.
- Expect to evaluate patient’s serum potassium level 1 week after spiraonolactone therapy begins, after each dosage adjustment, monthly for the first 3 months, quarterly for 1 year, and then every 6 months thereafter or as ordered. Notify prescriber if level exceeds 5 mEq/L or patient’s renal function deteriorates (serum creatinine level exceeding 4 mg/ dl). If patient has severe heart failure, follow closely because hyperkalemia may be fatal in such patients.
- Evaluate spironolactone’s effectiveness by assessing blood pressure and edema.
- Stop drug for several days, as prescribed, before patient undergoes adrenal vein catheterization to measure serum aldosterone level and plasma renin activity
2.Eplerenone
| Eplerenone |
| Availability Tablets: 25 mg, 50 mg |
| Indications and dosages ➣ Hypertension Adults: 50 mg/day P.O. as a single dose. After 4-week trial, may increase to 50 mg P.O. b.i.d. if necessary ➣ Heart failure; post-myocardial infarction (MI) Adults: Initially, 25 mg P.O. once daily. After 4 weeks, may increase to maximum dosage of 50 mg P.O. once daily. |
Mechanism of Action
Blocks the binding of aldosterone at its mineralocorticoid receptor sites located in the kidneys, heart, blood vessels, and brain. This action decreases blood pressure by preventing aldosterone from inducing sodium reabsorption and possibly other mechanisms that contribute to raising blood pressure.
Pharmacokinetics
- Half-Life: 3.5-6 hr
- Peak Plasma Time: 1-2 hr
- Bioavailability: 69%
- Protein Bound: 50%
- Metabolism: primarily hepatic CYP3A4
- Excretion: feces (32%) and urine (67%)
Administration
- Give with or without food.
- Know that drug may be given alone or with other antihypertensives.
Contraindications
- Hypersensitivity to drug
- Hyperkalemia
- Potassium supplements or potassiumsparing diuretics
- Type 2 diabetes mellitus with microalbuminuria
- Severe renal impairment
Precautions :
- Hepatic impairment
- Pregnant or breastfeeding patients
- Children (safety and efficacy not established).
Adverse reactions
- CNS: headache, dizziness, fatigue
- CV: angina, MI
- GI: diarrhea, abdominal pain
- GU: albuminuria, vaginal bleeding, changes in sexual function, gynecomastia and breast pain (in men)
- Metabolic: hypercholesterolemia, hyperkalemia
- Respiratory: cough
- Other: flulike symptoms
Patient monitoring
- Monitor electrolyte levels, and watch for signs and symptoms of hyperkalemia.
- Check vital signs, and ask patient about chest pain.
- Monitor lipid panel.
- Assess for new onset of persistent dry cough or flulike symptoms.
Patient teaching
- Advise patient to immediately report chest pain, flulike symptoms, or persistent dry cough.
- Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
- Inform patient that drug may affect sexual function. Encourage him to discuss this issue with prescriber.
- Advise female patient to discuss pregnancy or breastfeeding with prescriber before starting drug.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.
Nursing Considerations
- Monitor patient’s blood pressure regularly to evaluate eplerenone effectiveness.
- Monitor patient’s serum potassium level every 2 weeks for the first month or two of therapy and monthly thereafter, as ordered. • Be aware that patients who take an ACE inhibitor or an angiotensin II receptor antagonist during eplerenone therapy have an increased risk of hyperkalemia
3.Amiloride
| Amiloride |
| Availability Tablet 5mg |
| Indications and Dosages As adjunct to thiazide or loop diuretic in patient with heart failure or hypertension to correct diuretic-induced hypokalemia or to prevent diuretic-induced hypokalemia that increases the risk of arrhythmias or other complications Adults. 5 to 10 mg daily as single dose; if hypokalemia persists, increased to 15 mg daily and then 20 mg daily |
Pharmacokinetics
- Half-Life: 6-9 hr
- Peak Plasma Time: 3-4 hr
- Bioavailability: 30-90%
- Protein Bound: 23%
- Metabolism: NOT metabolized in the liver; no active metabolites
- Excretion Urine: 50%, Feces: 40-50%
Mechanism of Action
Inhibits sodium reabsorption in distal convoluted tubules and cortical collecting ducts, causing sodium and water loss and enhancing potassium retention.
Contraindications
Hypersensitivity to amiloride; impaired renal function; serum potassium level above 5.5 mEq/L; therapy with another potassium sparing diuretic, such as spironolactone or triamterene, or a potassium supplement
Adverse Reactions
- CNS: Confusion, depression, dizziness, drowsiness, encephalopathy, fatigue, headache, insomnia, nervousness, paresthesia, somnolence, tremor, vertigo
- CV: Angina, arrhythmias, orthostatic hypotension, palpitations
- EENT: Dry mouth, increased intraocular pressure, nasal congestion, tinnitus, vision disturbances
- GI: Abdominal pain or fullness, anorexia, appetite changes, constipation, diarrhea, GI bleeding, heartburn, indigestion, nausea, thirst, vomiting
- GU: Bladder spasms, dysuria, impotence, loss of libido, polyuria
- HEME: Aplastic anemia, neutropenia
- MS: Arthralgia, muscle spasms or weakness
- RESP: Cough, dyspnea
- SKIN: Alopecia, jaundice, pruritus, rash
- Other: Dehydration, hyperchloremia, hyperkalemia, hypernatremia, metabolic acidosis
Nursing Considerations
- Administer amiloride with food to reduce GI upset and early in the day to minimize sleep interference from polyuria.
- Monitor renal function test results, fluid intake and output, and weight. Also monitor serum potassium level to detect hyperkalemia.
Patient Teaching
- Warn patient to avoid high-potassium food and salt substitutes that contain potassium.
- Advise patient to consult prescriber before taking other drugs, including OTC remedies, especially sympathomimetics.
- Tell patient to report dizziness, trembling, numbness, and muscle weakness or spasms.
- Advise patient to increase fluid and fiber intake to prevent constipation.
- Warn patient to expect reversible hair loss and impotence.
4.Triamterene
| Triamterene |
| Availability Capsule 50mg,100mg |
| Indications and Dosages To treat edema in cirrhosis, heart failure, and nephrotic syndrome Adults. Initial: 25 to 100 mg daily. Maximum: 300 mg daily |
Mechanism of Action
Inhibits sodium reabsorption in distal convoluted tubules and cortical collecting ducts, causing sodium and water loss and enhancing potassium retention.
Contraindications
Anuria, diabetic nephropathy or renal disease linked to renal insufficiency, hyperkalemia (potassium level of 5.5 mEq/L or more), hypersensitivity to triamterene or its components, severe hepatic dysfunction
Adverse Reactions
- CNS: Dizziness, fatigue, headache, weakness
- EENT: Dry mouth
- ENDO: Hyperglycemia, hypoglycemia
- GI: Diarrhea, nausea, vomiting
- GU: Azotemia, elevated BUN and serum creatinine levels, renal calculi
- SKIN: Jaundice, photosensitivity, rash
Nursing Considerations
- Be aware that triamterene shouldn’t be given to patient with creatinine clearance below 10 ml/min/1.73 m2 because this condition increases the risk of druginduced hyperkalemia.
- Monitor serum potassium level during therapy, especially in patient with renal impairment or diabetes mellitus. Also monitor patient’s BUN and serum creatinine levels to assess renal function and prevent hyperkalemia
- Monitor patient for irregular heartbeat, which is usually the first sign of hyperkalemia.
- If you suspect hyperkalemia, obtain an ECG tracing, as ordered. A widened QRS complex or an arrhythmia requires prompt additional therapy.
- Monitor laboratory test results and watch for signs of metabolic or respiratory acidosis, which may occur suddenly in patient with cardiac disease or uncontrolled diabetes mellitus.
- Monitor patient’s serum uric acid and sodium levels, as ordered, because triamterene may reduce uric acid clearance and increase the risk of gout and hyperuricemia. This drug also may worsen preexisting hyponatremia.
- Monitor CBC with differential because drug may increase the risk of megaloblastic anemia in patient with folic acid deficiency.
Patient Teaching
- Advise patient to take triamterene with food or milk
- Instruct patient to avoid exposure to excessive heat or sunlight to prevent dehydration and, possibly, photosensitivity.
- Explain to patient with a history of gout that drug may increase the risk of attack.
- Advise patient to notify prescriber about ineffective diuresis and unexplained weight gain during therapy.
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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