Comparing Furosemide To Torsemide

Ann asked

My mom was taking 10 mg of furosemide daily for edema before entering a nursing home. She died 4 months later and I noticed that 10 mg of Torsemide was listed on the pharmacy invoice instead of the furosemide. Mom just stopped eating and we didn't do a feeding tube. I see that Torsemide is more potent than furosemide. Please tell me that this difference would not have caused her to stop eating. We always just called it the "water pill" and I just thought the nursing home did what the hospital would do whenever my dad went into the hospital and would give something similar but always different name than what he was taking. I didn't realize the change of potency until I looked up everything on the invoice. I had moms Atenolol and Lisinopril written down but the water pill was a verbal transaction and I can see how by just saying it, they could sound similar. I'm sorry this is so long. Please edit as needed. Thank you.

Answer

Both torsemide and furosemide as classified as "loop diuretics" and have the same mechanism of action. Loop diuretics are the preferred diuretics in those with heart failure versus the more commonly used "thiazide" diuretics, that are more often used for hypertension.

Loop diuretics are the most potent diuretics, but studies show they don’t lower blood pressure as well as thiazides, which is why they aren't considered first-line treatment for high blood pressure. They do tend to have more potent diuretic effects and are used for edematous conditions like heart and renal failure.

Comparing Torsemide To Furosemide

Torsemide and furosemide work the same way and most guidelines do not recommend one drug over the other. Torsemide is thought to be slightly more potent on a per milligram basis than furosemide, but this isn't thought to be evidence for better outcomes in treating patients. The potency of torsemide is mostly because it is more bioavailable, meaning our bodies absorb it better than furosemide.

Torsemide comes in the following strengths:

• 5mg
• 10mg
• 20mg
• 100mg
• 10mg/ml solution for injection

Furosemide comes in the following strengths:

• 20mg
• 40mg
• 80mg
  
• 10mg/1mL oral solution
• 10mg/1mL solution for injection 
• 40mg/5mL oral solution

There are two main characteristics that differentiate furosemide and torsemide:

• Torsemide is better absorbed than furosemide. In addition, studies show that torsemide absorption is more consistent when compared to furosemide.

• Torsemide has a longer duration of action and half-life than furosemide. For this reason, torsemide is generally dosed once daily while furosemide is often dosed once to twice daily.

There haven't been many studies that have compared torsemide to furosemide in regard to efficacy for the treatment of heart failure, but in the studies that have been done, preliminatry evidence points to torsemide possibily being the loop diuretic of choice, even though furosemide is more commonly prescribed.

One large study concluded the following:

"Growing evidence demonstrates more favorable pharmacokinetic profiles of torsemide and bumetanide compared with furosemide. Furthermore, torsemide may be more efficacious and safer than furosemide in patients with HF."

• Hypokalemia
• Dry mouth
• Weakness
• Gout attacks
• Increased cholesterol
• Gastrointestinal issues (e.g. nausea)
• Metabolic alkalosis
• Hypomagnesemia
• Hyponatremia
• Oto-toxicity (high doses)

Neither torsemide nor furosemide are necessarily associated with loss of appetite, but both have been reported to cause general GI issues such as nausea, constipation and heartburn. There certainly is a chance that one agent may be tolerated in this regard than the other, but it would be relatively rare to have a complete loss of appetite on either agent.