What is the difference between bumetanide and torsemide (loop diuretics) in clinical practice?

From the Guidelines

Bumetanide and torsemide are not the same, as they differ in potency, duration of action, and bioavailability, with bumetanide being approximately 40 times more potent than furosemide and torsemide offering more consistent absorption and a longer duration of action. The key differences between bumetanide and torsemide lie in their pharmacological properties and clinical applications. Bumetanide has a duration of action of 4-6 hours, as indicated in the 2022 AHA/ACC/HFSA guideline for the management of heart failure 1, making it useful for patients requiring high-dose diuresis but with limited oral intake capacity. On the other hand, torsemide has a longer duration of action of 12-16 hours, allowing for once-daily dosing and potentially reducing nighttime urination.

Some of the main differences between these two loop diuretics include:

• Potency: Bumetanide is more potent than torsemide, with 1 mg of bumetanide equivalent to about 20 mg of torsemide, as seen in the dosage comparisons in the guideline 1.
• Bioavailability: Torsemide offers more consistent absorption with nearly 100% bioavailability, regardless of gastrointestinal edema, making it particularly valuable in heart failure patients.
• Duration of action: Torsemide has a longer duration of action compared to bumetanide, which may influence the choice of medication based on patient needs and preferences.
• Additional properties: Torsemide demonstrates additional anti-aldosterone and anti-fibrotic properties that may provide cardiovascular benefits beyond diuresis.

When switching between these medications, the approximate equivalent doses are 1 mg bumetanide = 20 mg torsemide, as inferred from the dosage information provided in the guideline 1. Both medications can be administered orally or intravenously, with torsemide being preferred in heart failure due to its reliable absorption and longer action, while bumetanide may be chosen when higher potency in a smaller pill is needed or in patients with significant renal impairment. The choice between bumetanide and torsemide should be based on individual patient needs, considering factors such as the severity of heart failure, renal function, and the presence of gastrointestinal edema, as suggested by the clinical practice guidelines 1.

From the Research

Difference between Bumetanide and Torsemide

• Bumetanide and torsemide are both loop diuretics, but they have some differences in terms of their pharmacokinetics and potency 2.
• Torsemide has a longer duration of action and can be administered once daily, whereas bumetanide has a shorter duration of action and may require more frequent dosing 3, 2.
• Torsemide has a more reliable bioavailability compared to furosemide, but there is no direct comparison with bumetanide in terms of bioavailability 3.
• The rank order of potency is bumetanide > piretanide = torsemide > furosemide, although efficacy appears to be the same 2.

Clinical Practice

• In patients with chronic heart failure, torsemide may have a more favorable effect on mortality compared to bumetanide and furosemide, although the results are not consistent across all studies 4, 5.
• Torsemide may also have a more favorable effect on hospitalizations and New York Heart Association functional classifications in patients with heart failure 5.
• In patients with cirrhosis, torsemide may increase natriuresis and total volume diuresed compared to furosemide, but there is no significant difference in terms of plasma renin and aldosterone concentrations 5.
• In patients with pulmonary hypertension, torsemide may improve central venous pressure, capillary wedge pressure, and stroke volume, but the results are not statistically significant 5.

Pharmacokinetics

• The half-life of bumetanide is considerably longer in neonates than in adults, and the clearance is reduced at birth 6.
• The volume of distribution of furosemide undergoes little variation during neonate maturation, but the dose of furosemide may need to be adjusted based on the patient's age and weight 6.
• Bumetanide is more potent than furosemide, and its dose may be lower due to its increased potency 6.