Is there a diuretic that doesn't affect the kidneys as much as Lasix (furosemide) in elderly patients with Chronic Kidney Disease (CKD)?

Diuretic Selection in Elderly CKD Patients: Moving Beyond Furosemide

For elderly patients with CKD requiring diuretic therapy, torsemide is the preferred loop diuretic over furosemide due to its longer duration of action (12-16 hours vs 6-8 hours), once-daily dosing that improves adherence, and superior efficacy in this population. 1

Why Torsemide Over Furosemide

Loop diuretics remain the first-line diuretic class for CKD patients, particularly when GFR falls below 30 mL/min, as they maintain effectiveness even with markedly impaired renal function. 1 However, not all loop diuretics are equal:

• Torsemide provides 12-16 hour duration of action compared to furosemide's 6-8 hours, reducing the burden of multiple daily doses in elderly patients who often struggle with polypharmacy. 2, 1
• Maximum daily dose of torsemide is 200 mg versus furosemide's 600 mg, suggesting greater potency per milligram. 2, 1
• Once-daily dosing improves medication adherence, a critical factor in elderly populations with CKD. 1

The Problem with Furosemide in Elderly CKD

Furosemide's short duration of action creates several challenges in elderly CKD patients:

• Requires at least twice-daily dosing for adequate effect, increasing pill burden and risk of non-adherence. 2
• Reduced bioavailability in heart failure due to gut wall edema, a common comorbidity in elderly CKD patients. 2
• Diminishing effect with repeated dosing - the maximal diuretic effect occurs within 1.5 hours of the first oral dose, with up to 25% reduced effect on subsequent doses at the same concentration. 2
• Higher doses needed as GFR declines due to reduced tubular secretion and fewer nephron sites for drug action. 2

Alternative Thiazide-Like Diuretics: Chlorthalidone

Chlorthalidone can be considered in elderly CKD patients with resistant hypertension, even with advanced CKD (GFR <30 mL/min), contrary to traditional teaching. 2, 3

The European Society of Cardiology guidelines specifically note that thiazides should not be automatically discontinued when eGFR decreases below 30 mL/min/1.73 m². 2 Recent evidence challenges the long-held belief that thiazides are ineffective in advanced CKD:

• Chlorthalidone (25 mg) demonstrated BP reduction of 10.5 mm Hg in patients with mean eGFR of 26.8 mL/min/1.73 m² after 12 weeks. 2
• Duration of action is 24-72 hours, providing sustained effect with once-daily dosing. 2
• Superior to hydrochlorothiazide for 24-hour ambulatory BP control, with the largest difference occurring overnight. 2
• More effective than furosemide at increasing fractional excretion of sodium and chloride in severe renal failure patients in head-to-head trials. 4

Critical Monitoring Requirements for Chlorthalidone

The European Society of Cardiology designates thiazides as potentially inappropriate medications (PIMs) in elderly with CrCl <30 mL/min due to specific risks. 2 When using chlorthalidone in this population:

• Check electrolytes and eGFR within 2-4 weeks of initiation or dose escalation. 2
• Monitor closely for hyponatremia, which carries heightened risk in the elderly. 2
• Watch for hypokalaemia, volume depletion, and acute kidney injury. 2, 3
• Avoid in patients with history of gout, diabetes, or hyperlipidemia where possible. 2

Combination Therapy for Resistant Cases

When monotherapy with torsemide proves insufficient:

• Add chlorthalidone to torsemide for synergistic effect by blocking distal sodium reabsorption. 1, 5
• Combined hydrochlorothiazide-furosemide produces marked diuresis in patients with poor response to either agent alone, with significant reductions in weight, plasma volume, and mean arterial pressure. 5
• Consider spironolactone (if K+ <5.0 mmol/L and creatinine <2.5 mg/dL) to counter hypokalemia and improve resistant hypertension. 2, 1

Common Pitfalls to Avoid

• Failing to increase loop diuretic doses in advanced CKD - higher doses are required due to reduced kidney perfusion and fewer functional nephrons. 2, 1
• Using furosemide once daily when twice-daily dosing is needed for sustained effect. 1
• Automatically discontinuing thiazides at GFR <30 mL/min without assessing individual risk-benefit. 2
• Not monitoring magnesium levels - hypomagnesemia makes hypokalemia resistant to correction. 1
• Continuing diuretics during acute illness with vomiting or diarrhea without dose adjustment, risking volume depletion and AKI. 2

Practical Algorithm

1. Start with torsemide 10-20 mg once daily as first-line loop diuretic in elderly CKD patients. 1
2. Titrate torsemide up to 200 mg daily if needed before adding second agent. 1
3. Add chlorthalidone 12.5-25 mg daily for resistant hypertension or edema (if K+ and Na+ stable). 2, 1
4. Check electrolytes and renal function within 3 days and at 1 week, then monthly for 3 months. 1
5. Consider spironolactone 12.5-25 mg if hypokalemic and BP remains uncontrolled. 1