What is the difference between torsemide and furosemide (Lasix) in the treatment of heart failure?

Torsemide vs Furosemide in Heart Failure Treatment

Torsemide offers superior pharmacokinetic properties compared to furosemide, including better oral bioavailability and longer duration of action, but shows no significant difference in mortality outcomes based on the most recent high-quality evidence. 1

Pharmacological Differences

• Torsemide has greater oral bioavailability compared to furosemide, making its absorption more predictable and consistent, especially important in patients with intestinal edema from heart failure 1
• Torsemide has a longer duration of action than furosemide, potentially allowing for more sustained diuretic effect 1
• Preclinical and clinical data suggest torsemide may have favorable modulation effects on the renin-angiotensin-aldosterone system (RAAS) with possible underlying disease modification effects in heart failure 1

Clinical Outcomes

Mortality and Hospitalization

• The most recent and highest quality evidence from the TRANSFORM-HF trial showed no significant difference in 12-month all-cause mortality between torsemide and furosemide (26.1% vs 26.2%; HR 1.02,95% CI 0.89-1.18) 2
• No significant difference was found in the combined outcome of all-cause mortality or all-cause hospitalization over 12 months (47.3% with torsemide vs 49.3% with furosemide; HR 0.92,95% CI 0.83-1.02) 2
• Earlier meta-analyses suggested torsemide might reduce heart failure hospitalizations (RR 0.60; 95% CI, 0.43-0.83) and cardiovascular hospitalizations (RR 0.72; 95% CI, 0.60-0.88) compared to furosemide 3
• Some older studies indicated lower cardiac mortality with torsemide compared to furosemide (1.5% vs 4.4%; OR 0.37,95% CI 0.20-0.66) 4

Symptoms and Quality of Life

• TRANSFORM-HF found no significant difference between torsemide and furosemide in change from baseline in Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (adjusted mean difference 0.06,95% CI -2.26 to 2.37) 5
• Earlier studies suggested torsemide might provide more improvement in NYHA functional class compared to furosemide (72.5% vs 58% improvement from class III/IV to I/II; OR 2.32,95% CI 1.32-4.1) 4
• Some studies reported improvements in fatigue scores with torsemide compared to furosemide 6

Clinical Application

• Both torsemide and furosemide are FDA-approved for the treatment of edema associated with heart failure 7, 8
• Loop diuretics remain the cornerstone of volume management in heart failure and should be combined with guideline-directed medical therapy including ACE inhibitors and beta-blockers 1
• The usual daily dose range for torsemide is 10-20 mg compared to 40-240 mg for furosemide 1
• Diuretic dosing should be adjusted to eliminate clinical evidence of fluid retention while monitoring for electrolyte imbalances, hypotension, and azotemia 1

Practical Considerations

• Consider switching from furosemide to torsemide in patients with:
  • Variable or unpredictable response to furosemide 1
  • Intestinal edema that may impair furosemide absorption 1
  • Need for more consistent diuretic effect throughout the day 1
• Caution: When switching between loop diuretics, be aware that 10-20 mg of torsemide is approximately equivalent to 40-80 mg of furosemide 1
• Monitor for electrolyte imbalances, especially hypokalemia and hypomagnesemia, with either agent 1

Conclusion

While torsemide has theoretical pharmacokinetic advantages over furosemide, the most recent high-quality evidence from the TRANSFORM-HF trial does not demonstrate a mortality benefit or improvement in quality of life. The choice between these two loop diuretics should consider the individual patient's absorption issues, dosing convenience, and response to therapy.