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CARDIOVASCULAR SYSTEM › DIURETICS › DIURETICS AND POTASSIUM-SPARING AGENTS IN COMBINATION › High-ceiling diuretics and potassium-sparing agents
furosemide and potassium-sparing agents
C03EB01
Forms & Strengths
- Furosemide 20 mg / Spironolactone 25 mg tablets
- Furosemide 40 mg / Spironolactone 25 mg tablets
- Furosemide 40 mg / Triamterene 50 mg capsules
- Furosemide 80 mg / Triamterene 50 mg capsules
- Furosemide 20 mg / Amiloride 2.5 mg tablets
Adult Dosing
- Edema associated with heart failure, cirrhosis, or nephrotic syndrome: 1 tablet daily to TID, adjusted based on response and serum potassium levels
- Hypertension: Initial 1 to 2 tablets daily, titrated according to blood pressure and electrolyte monitoring
Pediatric Dosing
- Safety and efficacy in pediatric patients have not been established; use is generally not recommended
Indications
- Edematous conditions requiring a potent loop diuretic combined with potassium conservation (e.g., heart failure, hepatic cirrhosis, nephrotic syndrome)
- Management of hypertension where potassium depletion induced by loop diuretics must be prevented
Mechanism of Action
- Furosemide inhibits the Na+/K+/2Cl- cotransporter in the thick ascending limb of the loop of Henle, causing profound diuresis and natriuresis
- Potassium-sparing agents (spironolactone, triamterene, amiloride) act in the distal convoluted tubule and collecting duct to inhibit sodium reabsorption and potassium excretion through various mechanisms (aldosterone antagonism or direct epithelial channel blockade)
Contraindications
- Anuria
- Acute renal failure or severe progressive renal disease
- Hyperkalemia (serum potassium > 5.5 mEq/L)
- Hypersensitivity to furosemide, sulfonamide-derived drugs, or the specific potassium-sparing agent
- Concomitant use of other potassium-sparing agents or potassium supplements
Adverse Reactions
- Hyperkalemia
- Hyponatremia and hypovolemia
- Hypotension and dizziness
- Dehydration and acute kidney injury
- Gastrointestinal disturbances (nausea, diarrhea, cramping)
- Gynecomastia and menstrual irregularities (specifically with spironolactone components)
- Ototoxicity and photosensitivity (associated with furosemide)
Drug Interactions
- ACE inhibitors, ARBs, or direct renin inhibitors: Increased risk of severe hyperkalemia and acute renal failure
- Potassium supplements or salt substitutes containing potassium: Contraindicated due to high risk of life-threatening hyperkalemia
- Lithium: Decreased renal clearance of lithium, leading to potential lithium toxicity
- NSAIDs: May attenuate the diuretic, natriuretic, and antihypertensive effects, and increase nephrotoxicity risk
- Other antihypertensives or vasodilators: Potentiation of hypotensive effects
Curated Content: Needs Vetting Before Put to Clinical Use