Torsemide vs. Furosemide

Diuretics are a critical component of the pharmacotherapy of congestive heart failure,typically pulmonary edema or ascites.Furosemide has been, and remains, the diuretic of choice for acute and chronic management of CHF in both humans and animals. However, interesting alternatives and adjunctive therapies are now available, including Torsemide. Torsemide a loop diuretic can be used as an adjunct or alternative to furosemide.Loop diuretics, in general, exemplify the phrase “double-edged sword”.They are typically necessary often lifesaving.

Furosemide

For nearly 50 years, furosemide has been a workhorse for cardiologists and internists. It has undoubtedly saved countless lives when used to manage acute and emergent heart failure and has increased the longevity of patients when used long term.

Furosemide is typically?not?used as a monotherapy but rather given concurrently with:

Inotropes:?Pimobendan, digoxin, or dobutamine

Other diuretics:?Thiazides and/or potassium-sparing diuretics

Vasodilatators:?Angiotensin-converting enzyme (ACE) inhibitors, amlodipine, hydralazine, or nitroprusside

Antiarrhythmic agent:?Lidocaine, sotalol, or amiodarone

Furosemide is the diuretic of choice for everyday use because it is potent, rapid in onset, relatively inexpensive, and enjoys a comfort level with clinicians based on years of clinical experience. However, its rapid onset but short duration of action and association with diuretic resistance supports consideration of alternative loop diuretics, such as torsemide.

Torsemide

Torsemide has been shown to have a greater bioavailability, longer half‐life and longer duration of action than furosemide in human patients where it has been successfully used as an alternative to other diuretics such as furosemide.

Torsemide was found to have no effect on blood pressure in healthy dogs and no abnormalities were seen in the ECG.Diet consumption assessment shows that inappetence was associated with torasemide administration. A reduction of food consumption was also noted and it was more often in a females.

Advantages of torsemide over furosemide:

Better diuresis

Longer acting diuresis

Smoother diuresis

Improvement in cardiac function

Reduced fibrosis

Less potassium loss in urine

Aldosterone receptor blocker

Two veterinary studies have addressed torsemide pharmacodynamics, each showing superior diuresis when compared with furosemide.

Dogs receiving torsemide had a longer time to endpoint and were less than half as likely to experience death, euthanasia. Torsemide was noninferior to furosemide as first line PO treatment for new onset congestive heart failure caused by degenerative mitral valve disease.

Torsemide significantly decreased risk of cardiac‐related death or premature study withdrawal for cardiac reasons compared to furosemide.

Many studies of torsemide in dogs are observational and utilize torsemide as either a rescue agent in dogs refractory to high doses of PO furosemide or as a replacement for furosemide in dogs with less severe CHF. Torsemide was noninferior to furosemide with respect to alleviation of clinical signs of dyspnea, cough, and exercise intolerance, as well as evidence of ascites and radiographic signs of pulmonary edema, but most dogs already were receiving furosemide to treat previous or current signs of CHF. Torsemide was significantly associated with less than half the risk of cardiac death or euthanasia or worsening CHF as compared to furosemide. Death or euthanasia for cardiac reasons occurred in 10/12 (83.3%) dogs receiving torasemide and in 11/11 (100%) dogs receiving furosemide.Renal insufficiency, primarily reported as BUN or serum creatinine concentrations above the normal reference range, comprised the majority of renal or urinary disorders and was more commonly reported in the torasemide group.

Cortical subcapsular cysts (1–4?mm in diameter) with clear fluid content were observed in the kidneys in both of the overdose groups(torsemide and furosemide).On the kidneys of dogs administered torsemide ,there wasn't subcapsular cysts. In beagle dogs with high doses of the diuretics furosemide and muzolimine were associated with subcapsular cyst formation.

The effects of torsemide on other important patient‐centered endpoints such as quality of life, heart failure class, and hospitalization in human patients with CHF generally favor torasemide.Efficacy of torsemide was achieved using once daily dosing, and owner compliance was significantly improved during the primary treatment period. Previous guidelines regarding treatment of CHF caused by myxomatous mitral valve disease (MMVD) in dogs specifically point to owner noncompliance as a cause of so‐called diuretic resistance, and improving compliance ostensibly will lead to better resolution of CHF during the initial treatment period. Moreover, the need to frequently administer medications to a sick pet has the potential to negatively affect both the pet and pet owner's quality of life.

References:https://todaysveterinarypractice.com/cardiology/practical-techniques-navc-institutebeyond-furosemide-role-diuretics-congestive-heart-failure-part-1-torsemide/

https://onlinelibrary.wiley.com/doi/full/10.1111/jvp.13030

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7517836/