From the Guidelines
Torsemide should be dosed at approximately one-fourth to one-half the dose of furosemide, considering its higher potency and better oral bioavailability, as indicated in the 2022 AHA/ACC/HFSA guideline for the management of heart failure 1. When comparing the dosing of torsemide to furosemide, it's essential to consider the differences in their pharmacokinetic profiles. Torsemide has a longer duration of action, ranging from 12 to 16 hours, compared to furosemide's 6 to 8 hours 1. This longer duration of action can provide more consistent diuresis and potentially better symptom control in conditions like heart failure. Key differences between torsemide and furosemide include:
- Initial daily dose: Torsemide is typically started at 10-20 mg once daily, while furosemide is usually started at 20-40 mg once or twice daily 1.
- Maximum total daily dose: The maximum total daily dose for torsemide is 200 mg, compared to 600 mg for furosemide 1.
- Oral bioavailability: Torsemide has a higher oral bioavailability, ranging from 80-100%, compared to furosemide's 50-60% 1. When converting patients from furosemide to torsemide, it's recommended to start with torsemide at about one-fourth to one-half of the total daily furosemide dose, considering the differences in potency and bioavailability 1.
From the Research
Dosing Comparison of Torsemide and Furosemide
- The dosing of torsemide compared to furosemide can be considered based on their potency and effectiveness in promoting natriuresis and diuresis 2, 3.
- A dose equivalence of approximately 40 mg oral furosemide:10 mg oral torsemide resulted in similar natriuresis 3.
- However, a study found that a dose equivalence of approximately 4:1 resulted in similar natriuresis, suggesting that torsemide may be more potent than furosemide 3.
- The choice of dose may depend on the individual patient's response and the specific clinical context, as higher doses of torsemide may result in greater natriuresis but also increased neurohormonal activation and kidney dysfunction 3, 4.
Clinical Outcomes and Safety
- Torsemide was associated with a slightly lower risk of a composite of all-cause mortality or heart failure hospitalization and urgent visits with intravenous diuretics, but a slightly higher risk of acute kidney injury compared to furosemide 4.
- A meta-analysis found that torsemide was associated with significant improvement in functional status and lower cardiac mortality, and numerically fewer hospitalizations in patients with heart failure compared to furosemide 5.
- The safety profiles of torsemide and furosemide were similar, with no significant differences in hypokalemia or hypovolemia 4.
Pharmacokinetic and Pharmacodynamic Parameters
- Torsemide had a lower kidney bioavailability compared to furosemide, but a similar duration of action 3.
- Furosemide had a longer duration of kidney drug delivery and natriuresis compared to torsemide 3.
- The pharmacokinetic and pharmacodynamic parameters of torsemide and furosemide may influence their dosing and clinical outcomes 2, 3.