Diuretics (Water Pills) — List of Drugs and Mechanism of Action

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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