Metolazone Dose Escalation Timeline
The dose of metolazone should be increased from 2.5 mg to 5 mg after 3-5 days if weight loss and natriuresis are inadequate. 1
Initial Dosing and Monitoring
- The American College of Cardiology recommends starting with a low dose of metolazone (2.5 mg once daily) when adding to an existing loop diuretic regimen 2, 3
- Metolazone should be administered 30 minutes before the loop diuretic for optimal synergistic effect through sequential nephron blockade 2, 3
- Baseline serum electrolytes, creatinine, and blood pressure should be checked before starting metolazone 2
- Daily weight monitoring with target weight reduction of 0.5-1.0 kg per day should be implemented 3
Dose Escalation Protocol
- If weight loss and natriuresis are inadequate, the dose of both oral diuretics (metolazone and loop diuretic) can be increased simultaneously every 3-5 days 1
- The maximum recommended daily dose of metolazone is 10 mg 1, 2
- Electrolytes, renal function, and blood pressure should be rechecked 1-2 days after initiating therapy and after each dose adjustment 2, 1
Potential Complications to Monitor
- Severe electrolyte and volume depletion can occur when metolazone is combined with a loop diuretic 3
- Watch for hypokalemia (occurs in up to 80% of patients when used without potassium-sparing agents) 4
- Monitor for hyponatremia, which is more common with higher doses 5
- Observe for worsening renal function, which may occur with combination diuretic therapy 5
Special Considerations
- Metolazone maintains efficacy even at lower glomerular filtration rates, unlike other thiazides that lose effectiveness when GFR falls below 30-40 ml/min 2
- For patients with severe renal insufficiency, more careful monitoring is required as the risk of adverse effects is higher 3
- Consider hospital admission for initiation of combination therapy in high-risk patients (elderly, severe heart failure, baseline renal dysfunction) 3