Group
Chemical nature
Prototype drug(s)
Site of action
Mechanism of action
Relative natriuretic potency
Osmotic diuretics
Polysaccharide
Mannitol
Predominantly proximal tubule and loop of Henle
Inhibition of tubular reabsoption of solute and water
Dose-dependent (> 10 %)
Carbonic anhydrase inhibitors
Sulfonamide
Acetazolamide
Proximal tubule
Inhibits carbonic anhydrase
1–3 %
Loop diuretics
Sulfonamide phenoxyacetic acid-derivative
Furosemide Bumetanide Torsemide Ethacrynic acid
Thick ascending Henle’s loop
Inhibit Na/K/2Cl cotransporter
20–25 %
Distal tubule diuretics
Benzothiadiazine or its derivatives
Chlorothiazide Hydrochlorothiazide Chlorthalidone Metolazone Indapamide
Early distal convoluted tubule
Inhibit Na/Cl cotransporter
5 %
K+– sparing diuretics
Steroid Pyrazine carboxamides Pteridine derivative
Amiloride Triamterene Spironolactone Eplerenone
Cortical collecting duct
Inhibit ENaC (amiloride and triamterene) Antagonize MR receptors (spironolactone and eplerenone)
1–3 %
Physiologic Effects of Diuretics
In addition to their actions on Na+ and water, diuretics exert several other physiologic effects in the kidney. These include changes in renal blood flow (RBF) , glomerular filtration rate (GFR) , concentration and dilution of urine, and excretion of several other electrolytes. The physiologic effects of diuretics are summarized in Table 5.2.
Table 5.2
Physiological effects of diuretics
Osmotic diuretics | CA-inhibitors | Loop diuretics | Thiazide diuretics | K+-sparing diuretics | |
|---|---|---|---|---|---|
Hemodynamics | |||||
RBF | ↑ ↑ | ↓ | ↑ | ↓ | NC |
GFR | ↑ | ↓ | NC | ↓ | NC |
Urinary excretion | |||||
Na+ | ↑ ↑ | ↑ | ↑ ↑ | ↑ ↑ | ↑ |
K+ | ↑ | ↑ | ↑ ↑ | ↑ | ↓ ↓ |
Cl− | ↑ | ↓ | ↑ | ↑ | ↑ |
HCO3 − | ↑ | ↑ ↑ | NC | NC | ↑ |
Ca2+ | ↑ | NC | ↑ ↑ | ↓ | NC |
Phosphate | ↑ | ↑ ↑ | ↑ | ↑ | NC |
Mg2+ | ↑ | NC | ↑ ↑ | ↑
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