When should Metolazone be given with Furosemide (Lasix)?

From the Guidelines

Metolazone should be given with furosemide (Lasix) when a patient has severe heart failure or resistant edema, and the combination is typically used when patients have become resistant to loop diuretics alone, with metolazone administered 2.5 to 5 mg PO once or twice daily with a loop diuretic, as per the guidelines 1. The combination of metolazone and furosemide is used to enhance diuretic effect in patients with severe heart failure or resistant edema.

• The standard dosing for metolazone is 2.5 to 5 mg PO once or twice daily with a loop diuretic, as outlined in the guidelines 1.
• The administration of metolazone with furosemide can cause profound diuresis, and patients should be monitored closely for dehydration, electrolyte abnormalities (particularly hypokalemia and hyponatremia), and renal dysfunction.
• Potassium supplementation is frequently required when using this combination, as the risk of electrolyte depletion is markedly enhanced when two diuretics are used in combination 1.
• The combination is typically used intermittently, such as 2-3 times per week, to avoid excessive fluid and electrolyte depletion, due to metolazone's long half-life (up to 20 hours). The guidelines from the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines 1 provide the most recent and highest quality evidence for the use of metolazone with furosemide in patients with severe heart failure or resistant edema.
• The European Heart Journal guidelines 1 also support the use of metolazone in combination with loop diuretics for patients with insufficient response to initial diuretic treatment, but the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines 1 provides more specific guidance on the dosing and administration of metolazone with furosemide.

From the Research

Combination Therapy with Metolazone and Furosemide

• Metolazone can be given with Furosemide (Lasix) in patients with refractory heart failure, as it has been shown to be effective in combination with loop diuretics 2.
• The combination of metolazone and furosemide should be used with caution due to the potential for severe electrolyte disturbances, including hyponatremia, hypochloremia, alkalosis, and hypokalemia 3.
• A low starting dose of metolazone (< or =5 mg) is recommended when used in combination with a loop diuretic, as it has been shown to be effective and relatively safe in outpatients with refractory heart failure 2.

Patient Monitoring

• Patients receiving metolazone and furosemide combination therapy should be closely monitored for signs of excessive diuresis, and the treatment should be stopped temporarily if necessary 4.
• The patient's weight should be carefully monitored to avoid excessive diuresis, and the doses of metolazone and furosemide should not be reduced as a means to control an active diuresis 4.

Efficacy of Combination Therapy

• The combination of metolazone and furosemide has been shown to be effective in reducing weight, blood pressure, plasma-sodium, and plasma-potassium in patients with refractory heart failure 2.
• However, the addition of intravenous chlorothiazide to metolazone and loop diuretic therapy did not result in improved diuresis in patients with acute decompensated heart failure refractory to loop diuretics and adjunctive oral metolazone 5.