Diuretics Review,Definitions,Notes, Images And Summary

Diuretics Definitions And Summary

CLASSIFICATION OF DIURETICS 2

Diuretic is an agent that increase urinary excretion of water and electrolytes >> ↑ urine volume.

Diuretics are drugs that increase the rate of urine flow. With the exception of osmotic diuretics, they act primarily by decreasing reabsorption of Na+, which in turn will decrease the reabsorption of Cl- and water.
So these drugs are: – saluretics primarily (= increase the excretion of NaCl) and
– diuretics secondarily (= increase the excretion of water)

Natriuretic >>agents that increase renal Na+ excretion>> decrease reabsorption of Na+ at different sites in the nephron , because natriuretics also increase water excretion >> they are usually called diuretics (water follows salt)

Aquaretic >> agents that alter water excretion>> increase excretion of solute-free water as osmotic diuretics & ADH-antagonists.

The ability of diuretics to increase both fluid & electrolyte loss has led to their clinical use in  management of abnormalities in fluid volume & electrolyte composition.

The aim of diuretic therapy is to enhance sodium (Na+) excretion>>promoting negative Na+ balance,the net result >>Na+  &  fluid loss leads to shrink extracellular fluid.

CLASSIFICATION OF DIURETICS:

  1. Based on the intensity of the diuretic effect: highly, moderately, and weakly effective diuretics.
  2. Based on effect on K+ excretion: K+ (and H+)-losing and K+ (and H+)-sparing diuretics.
  3. Based on the site and mechanism of diuretic action.

1-Based on the intensity of the diuretic effect>> highly effective, moderately effective and weak diuretics.

CLASSIFICATION OF DIURETICS 2

highly effective diuretics:

  • Loop diuretics (furosemide, bumetanide, torasemide, ethacrynic acid)
  • Mannitol infusion (at a high rate)

–Moderately effective diuretics:

Thiazides (chlorothiazide, hydrochlorothiazide = HCTZ)
Thiazide-like drugs (clopamide, indapamide, chlorthalidone)

–Weak diuretics:

  • Carbonic anhydrase inhibitors (acetazolamide)
  • Na+ channel inhibitors (amiloride, triamterene)
  • Aldosterone antagonists (spironolactone, eplerenone, canrenoate)
2-Based on effect on K+ excretion:

CLASSIFICATION OF DIURETICS 45

–K+ (and H+) losing diuretics 

  • Loop diuretics (furosemide, bumetanide, torasemide, ethacrynic acid)
  • Thiazides (chlorothiazide, hydrochlorothiazide)
  • Thiazide-like drugs (clopamide, indapamide, chlorthalidone)

–K+ (and H+) sparing diuretics 

  • Aldosterone antagonists (spironolactone, canrenoate, eplerenone)
  • Na+ channel inhibitors (amiloride, triamterene)

3-Based on the site and mechanism of diuretic action.

CLASSIFICATION OF DIURETICS 4

Diuretics can be subdivided according to the segment of nephron in which they work

– Proximal tubule: as Carbonic anhydrase inhibitors, Osmotic diuretics

– Loop of Henle: as Loop diuretics

– Early distal tubule: as Thiazide diuretics

-Late distal tubule & collecting duct: as Aldosterone antagonist & renal epithelial Na+ channel inhibitors

CLASSIFICATION OF DIURETICS 1

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