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Furosemide [fur oh' se mide]
Bumetanide [byoo met' a nide]
Ethacrynic acid [eth a krin' ic]
  • Furosemide, bumetanide, torsemide, and ethacrynic acid are "high-ceiling" loop diuretics acting primarily at the ascending limb of the loop of Henle.

  • The effectiveness of these agents is related to their site of action because reabsorption of about 30 - 40% of the filtered sodium and chloride load occurs at the ascending loop. Distal sites are not able to compensate completely for this magnitude of reduction of NaCl reabsorption.

  • Loop diuretics increase urinary Ca2+ in contrast to the action of thiazides.

  • Loop diuretics also increase renal blood flow by decreasing renal vascular resistance.

  • These drugs are beneficial in managing systemic and pulmonary fluid overload produced by congestive heart failure (CHF). By i.v. administration they are particularly effective in resolving acute pulmonary edema.

  • Adverse Effects

    • Ototoxicity

    • Furosemide and ethacrynic acid block renal excretion of uric acid by competition with renal secretory and biliary secretory systems.

      • Therefore these agents can precipitate gout.

    • Potassium depletion.