Is Metozolone a recognized medication?

Metolazone: A Recognized Diuretic Medication for Heart Failure

Yes, metolazone is a recognized medication. It is a thiazide-like diuretic specifically mentioned in clinical guidelines for heart failure treatment, particularly when used in combination with loop diuretics for diuretic resistance. 1

Medication Classification and Properties

• Metolazone is a modified quinazolinesulphonamide diuretic that belongs to the thiazide-like diuretic class 2
• Unlike traditional thiazide diuretics, metolazone remains effective even in patients with significantly reduced kidney function (glomerular filtration rate as low as 1.2 ml/min) 2
• It is specifically recognized in the American College of Cardiology/American Heart Association (ACC/AHA) heart failure guidelines as a treatment option 1

Clinical Applications

Primary Use in Heart Failure

• Metolazone is primarily used in combination with loop diuretics when diuretic resistance develops in heart failure patients 1, 3
• The ACC/AHA guidelines specifically recommend adding 2.5 mg of metolazone for 2-3 days to a loop diuretic when patients experience weight gain of 1-2 kg due to fluid retention 1
• It is particularly valuable in patients with refractory heart failure who no longer respond adequately to loop diuretics alone 3

Dosing Considerations

• The typical starting dose is low (≤5 mg) as documented in most clinical studies 3
• In chronic renal failure, higher doses (20-150 mg) have been studied and shown to be effective without significant side effects 2
• The ACC/AHA guidelines specifically mention 2.5 mg as an appropriate supplemental dose when added to loop diuretics 1

Efficacy

• Metolazone produces a significant increase in urine flow and sodium excretion even in patients with severely reduced kidney function 2
• When combined with loop diuretics, metolazone is as effective as chlorothiazide (another thiazide diuretic) in treating acute decompensated heart failure 4
• Studies show improvement in NYHA functional class when metolazone is added to loop diuretics in patients with refractory heart failure 3

Safety Considerations and Monitoring

Potential Adverse Effects

• Combination therapy with loop diuretics can cause significant electrolyte abnormalities, particularly hypokalemia and hyponatremia 3
• Clinically important hypokalemia (<2.5 mM) or hyponatremia (<125 mM) occurs in approximately 10% of treatment episodes 3
• Treatment can lead to increased blood urea nitrogen (BUN) and creatinine levels, indicating potential impact on kidney function 3

Monitoring Requirements

• Careful monitoring of electrolytes (particularly potassium and sodium) is essential when using metolazone, especially in combination with loop diuretics 1, 3
• Weight, blood pressure, and kidney function should be regularly assessed during treatment 3
• Severe electrolyte and volume depletion can occur when metolazone is combined with a loop diuretic, potentially requiring hospitalization in certain circumstances (hypotension, azotemia, oliguria, or ascites) 1

Important Clinical Considerations

• Metolazone should not be confused with metaxalone (a muscle relaxant) 5 or methocarbamol (another muscle relaxant) 6, which are entirely different medications with different uses and side effect profiles
• Metolazone is distinct from metamizole (dipyrone), which is an analgesic, antipyretic, and spasmolytic agent 7, 8
• When diuretic resistance develops, the combination of metolazone with a loop diuretic is an established and effective strategy 1, 3