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Study of Metolazone and Acetazolamide Combination for Patients with Acute Heart Failure and Volume Overload

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on patients with acute heart failure who have excess fluid in their body and may not respond well to standard water pill treatments. The research aims to find the most effective treatment strategy using two different medications: metolazone tablets and acetazolamide injection. These medications help remove excess fluid from the body.

The study will compare these medications with inactive treatments (placebo) that look identical to the real medicines. Some patients will receive metolazone tablets while others will get inactive tablets. Similarly, some patients will receive acetazolamide injections while others will get saline injections. The treatment period lasts for 4 days during the hospital stay.

The medications being tested are types of water pills (diuretics) that work differently from standard heart failure treatments. Metolazone is taken by mouth and helps the kidneys remove more water and salt from the body. Acetazolamide is given through an injection and works by reducing fluid buildup in the body through a different mechanism.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial admission

    Upon admission to the hospital with acute heart failure, your condition and eligibility for the study will be evaluated

    The medical team will check for signs of congestion (fluid retention), which may include swelling in legs, fluid in abdomen, or fluid in lungs

  2. Step 2

    Treatment assignment

    You will be assigned to receive one of the following medication combinations:

    Option 1: Metolazone tablets taken by mouth

    Option 2: Inactive tablets that look identical to metolazone

    Option 3: Acetazolamide given through injection

    Option 4: Saline solution given through injection that looks identical to acetazolamide

  3. Step 3

    Treatment period

    You will receive the assigned treatment during your hospital stay

    The medical team will monitor your response to treatment, including changes in fluid retention and kidney function

    Your weight and fluid balance will be regularly measured

  4. Step 4

    Hospital discharge

    You will be discharged from the hospital when your condition improves

    The number of days spent in the hospital will be recorded

  5. Step 5

    Follow-up period

    Your health status will be monitored for 90 days after starting the study

    The medical team will track your progress, including any hospital readmissions

    Your kidney function will be evaluated during this period

Who can join the trial?

9 criteria

  • Must be 18 years or older
  • Must be admitted to hospital with acute heart failure (a sudden worsening of heart failure symptoms)
  • Must show signs of diuretic resistance by meeting one of these conditions:
    • Taking water pills (loop diuretics) daily for at least 7 days before hospital admission
    • Not responding well enough to high-dose water pills in the last 24 hours (less than 500g weight loss or less than 1L fluid loss despite receiving high doses of IV furosemide)
    • Must have at least one of these signs of fluid overload:
      • Swelling in legs or feet that leaves a dent when pressed (pitting edema)
      • Fluid in the belly area (ascites)
      • Swollen neck veins (elevated jugular venous pressure)
      • Signs of fluid in the lungs seen on X-ray or ultrasound
      • Both men and women can participate

Who cannot join the trial?

14 criteria

  • Age below 18 years or above 85 years
  • Known allergy or hypersensitivity to diuretic medications
  • Severe kidney failure requiring dialysis (a medical procedure to filter blood when kidneys don't work properly)
  • Cardiogenic shock (a condition where the heart suddenly can't pump enough blood to meet the body's needs)
  • Pregnancy or breastfeeding
  • Participation in another clinical trial within the past 30 days
  • Life expectancy less than 6 months due to other medical conditions
  • Severe liver disease (poor liver function affecting blood clotting and metabolism)
  • Uncontrolled high blood pressure (systolic pressure above 180 mmHg)
  • Systemic infection (infection affecting the whole body) or active infection requiring antibiotics
  • Recent heart attack or stroke (within the last 30 days)
  • Unable to provide informed consent or follow study procedures
  • History of serious allergic reactions to medications
  • Severe mental illness that could interfere with study participation
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Investigated drugs

  • Furosemide

    is a diuretic medication (water pill) commonly used to treat heart failure. It helps remove excess fluid from the body by increasing urine production. This medication is particularly important for patients with acute heart failure who have too much fluid in their body.

  • Chlorothiazide

    is another type of diuretic that works differently from furosemide. It helps the kidneys remove excess water and salt from the body. When combined with other diuretics, it can help patients who don't respond well to a single diuretic medication.

  • Spironolactone

    is a potassium-sparing diuretic that not only removes excess fluid but also helps maintain the body's potassium levels. This medication is particularly useful in heart failure patients as it can help protect the heart while removing excess fluid.

  • Torsemide

    is a loop diuretic similar to furosemide but with longer-lasting effects. It helps remove excess fluid from the body and can be particularly helpful for patients who don't respond well to other diuretics.

What is already known about the treatment

  • Furosemide

    A potent loop diuretic medication administered either orally or through intravenous injection, commonly used as a first-line treatment for acute heart failure with volume overload. This medication works by inhibiting sodium and chloride reabsorption in the kidneys' loop of Henle, leading to increased water excretion and reduction of fluid overload in the body. Furosemide belongs to the class of loop diuretics and is well-established in medical literature with extensive clinical evidence supporting its effectiveness in managing heart failure symptoms and reducing fluid retention.

  • Torsemide

    An alternative loop diuretic medication available in both oral and intravenous forms, used in the treatment of acute heart failure and edema. The medication functions by blocking sodium and chloride reabsorption in the ascending loop of Henle, resulting in increased urine output and reduction of excess fluid in the body. Compared to furosemide, torsemide has better oral bioavailability and a longer duration of action, making it an effective option for patients with acute heart failure requiring diuretic therapy.

  • Bumetanide

    A potent loop diuretic medication that can be administered orally or intravenously, primarily used in treating fluid overload in acute heart failure patients. Like other loop diuretics, it works by preventing the reabsorption of sodium and chloride in the kidneys, leading to increased urine production and reduction of excess fluid volume. Bumetanide is particularly useful in patients who may be resistant to other diuretics, as it has a more predictable absorption profile and potent diuretic effect.

Investigated diseases

Acute Heart Failure - A sudden onset condition where the heart cannot pump enough blood to meet the body's needs. It occurs when the heart muscle becomes too weak or stiff to work properly, leading to fluid buildup in the lungs and other body tissues. Patients typically experience rapid breathing, fatigue, and swelling in the legs and ankles. The condition can develop quickly, often over hours or days, and frequently results in fluid overload throughout the body. Common signs include difficulty breathing, especially when lying down, and reduced ability to exercise or perform daily activities.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-510633-17-00Estimated enrolment939 patientsSponsorRegion Hovedstaden

sourced from the EU Clinical Trials Register and site verification

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