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Overview of the Different Diuretics
The following gives an overview of the different renal target structures as well as the achieved effects associated with them.
Carbonic anhydrase inhibitors
Active substances: Acetazolamide, dorzolamide, brinzolamide
Renal target structure: Proximal tubule inhibition of the carbonic anhydrase
Effect on the serum electrolytes:
- Decreased sodium and bicarbonate, increased protons
- Possibly hypokalaemia, hyperglycemia
Drainage Effectiveness: Not commonly used as a diuretic due to loss of electrolytes and bicarbonate
Loop diuretics
Active substances: Furosemide, bumetanide, piretanide, torasemide
Renal target structure: Thick ascending limb of the Henle loop, luminal Na-K-Cl-cotransporter, decreased reabsorption
Effect on the serum electrolytes: Decreased Na, K, Cl, Ca, Mg, decreased reabsorption of H2O in the collecting duct system (due to the changed osmotic gradient), possible hyperglycaemia, hyperuricaemia.
Drainage Effectiveness:
Most effective diuretic (20–30 % of the glomerular filtrates)
Thiazide diuretics and thiazide analogs
Active substances: Hydrochlorothiazide, chlorthalidone, mefruside, xipamide
Renal target structure: Early disinhibition of the Na-Cl-cotransporter, resulting in decreased NaCl reabsorption
Effect on the serum electrolytes:
- Decreased Na, Cl, Mg, decreased K (as a lot of Na can be exchanged for K in the late distal tubule)
- Increased Ca
- Possibly hyperglycaemia, hyperuricaemia
Drainage Effectiveness: Moderate effects (10–15 % of the glomerular filtrates)
Potassium-sparing diuretics
Active substances: Amiloride, Triamterene
Renal target structure:
- Late distal tubule and collecting duct system
- Inhibition of sodium channels
Effect on the serum electrolytes: Decreased Na, increased K
Drainage Effectiveness: Low effects (2–4% of the glomerular filtrates)
Aldosterone antagonists
Active substances: Spironolactone, potassium canrenoate, eplerenone
Renal target structure:
- Late distal tubule and collecting duct system
- Competitive inhibition at the cytosolic mineralocorticoid receptor
Effect on the serum electrolytes: Decreased Na, increased K
Drainage Effectiveness: Low effects (2–3 % of the glomerular filtrates)
Osmotic diuretics
Active substances: Mannitol, sorbitol
Renal target structure:
- Unspecific effect in the whole tubule lumen osmodiuretically
- Filtrated glomerularily and are not reabsorbed.
Effect on the serum electrolytes: Possible increased Na
Drainage Effectiveness: Low effects (2–3 % of the glomular filtrates)
Methylxanthines
Active substances: Theophylline, theobromine, caffeine
Renal target structure: Antagonist at the adenosine receptor (subtype A1), presumably inhibition of the basolateral Na-HCO3–cotransporter in the proximal tubule
Effect on the serum electrolytes: Decreased Na and HCO3, increased H
Drainage Effectiveness: Little usefulness as a diuretic due to adverse effects
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