Loop diuretics
Blocking NKCC2 in the loop of Henle, so much more salt and water is lost.
Also called high-ceiling diuretics.
Class card
- Drugs
- Furosemide, Bumetanide and Torasemide
- Used for
- Edema and fluid overload in heart failure
- Edema from cirrhosis, kidney disease or nephrotic syndrome
- Acute pulmonary edema
- High blood pressure
- Known for
- Low potassium
- Tinnitus and hearing loss (ototoxicity)
- Name stems
- -semide
4 cards: the class, and each drug in it.
Mechanism of action
How do loop diuretics work?
They block the Na-K-2Cl cotransporter (NKCC2) in the thick ascending limb of Henle's loop, reaching it from inside the tubule. Sodium, chloride and water are lost in large amounts, along with potassium, magnesium and calcium. The diuresis is strong and quick, and it still works when kidney function is poor.
The drugs
Loop diuretics with a card
- FurosemideShort acting: an intravenous dose works within 5 minutes and its diuresis lasts about 2 hours.
- BumetanideWeight for weight about 40 times as potent as furosemide, and oral doses work almost as well as intravenous ones.
- TorasemideChemically a pyridine-sulfonylurea, yet it is a loop diuretic, not a diabetes drug; it lasts longer than furosemide.
Uses
What are loop diuretics used for?
- Edema and fluid overload in heart failure
- Edema from cirrhosis, kidney disease or nephrotic syndrome
- Acute pulmonary edema
- High blood pressure
Side effects
Side effects of loop diuretics
- Low potassiumKnown forSerious
- Tinnitus and hearing loss (ototoxicity)Known forSerious
- Dehydration and low blood pressure
- Low sodium
- Low magnesium
- Low calcium
- Raised uric acid and gout
- Raised blood sugar
- Kidney injury from dehydration or interstitial nephritisSerious
- Passing large amounts of urine, with thirst
What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.
Watch for
Cautions
- Contraindicated in anuria.
- Aminoglycosides and other ototoxic drugs add to the risk of hearing loss.
- Lithium levels rise, and the low potassium they cause makes digoxin toxicity more likely.
- Sulfonamide allergy: cross-reactions can occur with furosemide and bumetanide.
Remember them
A way to remember them
OH DANG
- O
- Ototoxicity
- H
- Hypokalemia
- D
- Dehydration
- A
- Allergy to sulfonamides
- N
- Nephritis (interstitial)
- G
- Gout
A mnemonic widely used in teaching
Name stems
-semide means loop diuretic (furosemide type)
Furosemide and torasemide (US name torsemide) share it. Bumetanide, another loop diuretic, carries the stem -etanide instead.
- Every drug name stem
Don't mix them up
Classes easily confused with these
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Furosemide tablets: label (DailyMed)
- Furosemide injection: label (DailyMed)
- Bumetanide tablets: label (DailyMed)
- Torsemide tablets: label (DailyMed)
- Loop diuretic (NCI Thesaurus)
- Furosemide (NHS)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Heart failure, rhythm and angina
Practice loop diuretics with the other classes in this group: what each drug is, how it works, what it treats and what it's known for.
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