Diuretics Definitions And Summary
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:
- Based on the intensity of the diuretic effect: highly, moderately, and weakly effective diuretics.
- Based on effect on K+ excretion: K+ (and H+)-losing and K+ (and H+)-sparing diuretics.
- 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.
—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:
–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.
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
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Related Topics>>
- Thiazide diuretics
- Diuretics Drugs in treatment Hypertension
- Osmotic diuretics Notes, Images And Summary