Overview
This lecture covers potassium-sparing diuretics, focusing on their mechanism, uses, types, side effects, and important nursing and patient education points.
Mechanism of Action
- Potassium-sparing diuretics prevent loss of potassium while promoting sodium and water excretion in the kidney.
- They act mainly on the late distal tubule and collecting duct of the nephron.
- These drugs inhibit sodium channels or block aldosterone, reducing sodium reabsorption and potassium excretion.
- Results in diuresis (increased urine output) while sparing potassium, potentially leading to hyperkalemia (high potassium).
Types of Potassium-Sparing Diuretics
- Epithelial Sodium Channel Inhibitors: Block sodium channels directly (e.g., triamterene, amiloride).
- Aldosterone Antagonists: Block the action of aldosterone hormone (e.g., spironolactone, eplerenone).
Clinical Uses
- Treat hypertension (high blood pressure).
- Manage fluid overload (edema) in conditions like heart failure, liver impairment, nephrotic syndrome.
- Prevent or treat hypokalemia from other diuretics.
- Manage hyperaldosteronism (especially with aldosterone antagonists).
Nursing and Patient Education
- Monitor for dehydration: check blood pressure, heart rate, thirst, fatigue, and mental status changes.
- Track fluid intake and output and assess renal function (BUN, creatinine).
- Not recommended for patients with renal failure.
- Watch for signs of hyperkalemia: muscle cramps, weakness, paresthesia, nausea, vomiting, and ECG changes (tall peaked T-waves).
- Educate to avoid high-potassium foods (potatoes, pork, oranges, tomatoes, avocados, strawberries, spinach, fish, mushrooms, melons) and salt substitutes.
- Be aware of medication interactions: ACE inhibitors, ARBs, NSAIDs, and lithium (risk of lithium toxicity).
- Advise to take medication with food to reduce stomach upset.
- Spironolactone can cause anti-androgen effects: gynecomastia, menstrual irregularities, sexual dysfunction.
Key Terms & Definitions
- Diuretic — a drug that increases urine production.
- Nephron — the functional unit of the kidney, filtering blood and forming urine.
- Hyperkalemia — abnormally high potassium levels in the blood.
- Aldosterone — a hormone that increases sodium and water reabsorption in the kidney.
- Gynecomastia — enlargement of male breast tissue.
Action Items / Next Steps
- Take the quiz on potassium-sparing diuretics for review.
- Memorize normal potassium (3.5–5 mEq/L) and lithium (0.5–1.2 mmol/L) levels.
- Review signs/symptoms of hyperkalemia and educate patients accordingly.