In this episode, we review the pharmacology, pharmacokinetics, adverse effects, monitoring, medicinal chemistry, and more of loop diuretics.
Key Concepts
- Loop diuretics (furosemide, torsemide, bumetanide, ethacrynic acid) are the most potent type of diuretic and are used to relieve edema.
- Loop diuretics cause an increased loss of sodium, chloride, potassium, hydrogen, magnesium, and calcium ions into the urine. Excessive loss of these ions manifests as hypokalemia, hypomagnesemia, and metabolic alkalosis.
- Loop diuretics have an S-shaped dose response curve – a minimum dose is required for diuresis and a “ceiling” effect occurs at higher doses (leading to more ADRs). Doses should be individualized based on the clinical response of the patient.
- Ethacrynic acid is incorrectly used in patients with a “sulfa” allergy. The other loop diuretics contain a sulfa moiety but are safe for use in patients with “sulfa” allergy (e.g. allergy to sulfamethoxazole-trimethoprim).
- The TRANSFORM-HF trial strongly suggests that there is no clinical difference between furosemide and torsemide.
References
- Rachoin JS, Cerceo EA. Four nephrology myths debunked. J Hosp Med. 2011;6(5):E1-E5. doi:10.1002/jhm.703
- Strom BL, Schinnar R, Apter AJ, et al. Absence of cross-reactivity between sulfonamide antibiotics and sulfonamide nonantibiotics. N Engl J Med. 2003;349(17):1628-1635. doi:10.1056/NEJMoa022963
- Buggey J, Mentz RJ, Pitt B, et al. A reappraisal of loop diuretic choice in heart failure patients. Am Heart J. 2015;169(3):323-333. doi:10.1016/j.ahj.2014.12.009
- Mentz RJ, Anstrom KJ, Eisenstein EL, et al. Effect of Torsemide vs Furosemide After Discharge on All-Cause Mortality in Patients Hospitalized With Heart Failure: The TRANSFORM-HF Randomized Clinical Trial. JAMA. 2023;329(3):214-223. doi:10.1001/jama.2022.23924