Loop Diuretics

Loop Diuretics


Loop diuretics are effective in pulmonary edema, heart failure, nephrotic syndrome, acute and chronic renal insufficiency, hypertension, and cirrhosis. Loop diuretics are used in the treatment of hypertension if thiazides are not effective. Furosemide (Lasix), bumetanide (Bumex), torsemide (Demadex), and ethacrynic acid (Edecrin) are four diuretics that act on the ascending limb of the loop of Henle. These diuretics have the highest efficacy in mobilizing sodium and chloride from the body and are the drug of choice for reducing acute pulmonary edema with heart failure. Loop diuretics are relatively short acting with a quick onset and work for 12-24 hrs. Diuresis occurs over 4 hours after dose administration.


Side Effects:

  • Hypersensitivity reaction
  • Hypokalemia
  • Hyponatremia
  • Hypomagnesemia
  • Hypocalcemia (do not give to patients with renal stones)
  • hyperuricemia (may cause or exacerbate gout attacks)
  • Metabolic alkalosis-holding on to bicarb
  • Elevations in BUN and serum creatinine
  • hypergycemia
  • Ototoxicity (when Lasix is administered quickly intravenously, dose dependent, reversible)
  • Sulfonamide allergy (loop diuretics have a sulfa derivative, ethacrynic acid is reserved for those with a true allergic reaction to a loop or thiazide)
  • Risk of dehydration (>4L urine/24hrs)
  • Interaction if given with Li+ (thymoprofylatic drug). This interaction will lead to increase Li+ reabsorption and lead to toxicity.
  • May reduce levels of hypoglycemic agents
  • Levels of furosemide may be decreased by tekturna and NSAIDS
  • Furosemide may increase levels of ACE-I and antihypertensives


Loop Diuretics

Drug Name Bumetanide
Ethacrynic Acid
-Watch for clergy to sulfa
-Fast acting- 4 hours
-Volume unloader
MOAInhibit the cotransport of Na+/K+/Cl- in the luminal membrane in the ascending limb of the loop of Henle-↓ SERUMN Ca+
-↑ Ca+ in URINE
(kidney stones)
Drug Effects-↑Ca+ in urine
-↑K+ excretion
-↓renal vascular resistance and ↑ renal blood flow
-↑prostaglandin synthesis (NSAIDS can interfere with prostaglandid synthesis and ↓ diuretic action)
-High risk of dehydration if >4 L urine in 24 hours
-If given with Li+ (thymoprofylatic) it will ↓Na+ reabsorption & may lead to toxicity because of ↑ Li reabsorption
Therapeutic Uses-Acute pulmonary edema
-Severe renal failure
-Severe HTN
Drug of choice for ↓ acute pulmonary edema of heart failure
Side Effects-Ototoxicity
-Acute hypovolemia
-Hypokalemic Alkalosis (Potassium depletion)
Monitor BMP, CBC, & blood sugar



Edmunds, M. W., & Mayhew, M. S. (2014). Pharmacology for the primary care provider (4th ed.). St. Louis, MO: Elsevier Mosby.

Harvey, R. A., Clark, M. A., Finkel, R., Rey, J. A., & Whalen, K. (2012). Pharmacology (5th ed.). Baltimore, MD: Lippincott.