Torasemide !

A loop diuretic with reliable oral absorption and longer action than furosemide. Used for oedema and high blood pressure.

Updated 2026-11-01

Class: Loop diuretics
Transporter: Na⁺-K⁺-2Cl⁻ cotransporter (NKCC2) of the loop of Henle
ATC code: C03CA04

Also called: Torsemide

Na⁺-K⁺-2Cl⁻ cotransporter (NKCC2) of the loop of HenleTorasemide

The figure shows torasemide bound to human NKCC1, the closely related cotransporter found outside the kidney; NKCC2, the renal target, belongs to the same family and binds loop diuretics in the same way.

Target in 3D: Na⁺-K⁺-2Cl⁻ cotransporter (NKCC2) of the loop of Henle. PDB structure 9C0G (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Torasemide reaches the tubule lumen by secretion in the proximal tubule and blocks the Na⁺-K⁺-2Cl⁻ cotransporter (NKCC2) in the thick ascending limb. Sodium, chloride and water are lost in the urine, with potassium. Its good oral absorption gives a more predictable effect than furosemide.

Torasemide is secreted into the proximal tubule
It blocks NKCC2 in the thick ascending limb
Na⁺, Cl⁻ and water are lost; K⁺ too
Predictable oral effect: less oedema, lower pressure

Pharmacokinetics

Absorption: About 80% bioavailable by mouth, with little variation between people
Metabolism: Mostly by the liver (CYP2C9)
Elimination: Liver metabolism and urine
Half-life: About 3.5 hours

Indications

Oedema from heart failure Heart failure →
Oedema from kidney or liver disease Chronic kidney disease →
High blood pressure Arterial hypertension →

Adverse effects

Common

Increased urination
Dizziness and headache
Hypokalaemia
Muscle cramps

Contraindications

Anuria
Hepatic coma
Hypersensitivity to torasemide

Key interactions

Aminoglycosides or etacrynic acid: More ototoxicity
Warfarin, phenytoin or celecoxib (CYP2C9 substrates): Torasemide can raise their levels
Probenecid: Less torasemide reaches the tubule; weaker diuresis
Lithium: Less lithium clearance and risk of toxicity
Cholestyramine: Less torasemide absorbed; doses are separated

What is monitored

Potassium and other electrolytes
Kidney function
Blood pressure
Weight and fluid balance

Nursing care

Before giving: blood pressure, potassium and kidney function.
Daily weight and signs of dehydration.
Check INR more closely in patients on warfarin.
Teach: rise slowly, drink enough fluid in hot weather or with diarrhoea, report dizziness or fainting.

Pregnancy and breastfeeding

Not a usual treatment in pregnancy; used only if clearly needed.

Test yourself

Think of the answer, then tap the question to see it.

What is the advantage of torasemide over oral furosemide?

Its oral absorption is high and consistent between people, so its effect is more predictable.

Which enzyme metabolises torasemide, and which drugs does that affect?

CYP2C9; torasemide can raise levels of CYP2C9 substrates such as warfarin, phenytoin and celecoxib.

How does probenecid weaken torasemide?

It competes for secretion into the proximal tubule, so less torasemide reaches its site of action in the lumen.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - TORSEMIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); Torsemide: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2024); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); RCSB PDB - 9C0G: Phosphorylated human NKCC1 in complex with torsemide (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.