Diuretics act to promote sodium and water loss. They are used to treat hypertension (especially thiazides), heart failure, cirrhosis, nephrotic syndrome, and other causes of edema.









  • Loop Diuretics
  • Thiazides
  • Potassium Sparing
  • Osmotic
  • Other

Loop Diuretics

Loop diuretics are powerful drugs that inhibit Na, Cl, and K reabsorption in the thick ascending limb, possibly be competing with chloride. This drop in Na and K resorption leads to diuresis and kaluresis.


A loss of renal concentrating and diluting capacity leads to impaired preservation of water and electrolytes during periods of dehydration.

Hypokalemia, hypomagnesemia, and occasionally hyponatremia can be due to loop diuretic use. Furosemide (Lasix) is the most common loop diuretic.


Thiazides are key drugs in treating hypertension. They inhibit NaCl transport into the distal convoluted tubule, preserving loop function.


Hyponatremia is fairly common as volume contraction engages ADH and much free water is reabsorbed. Electrolytes need to be monitored after beginning therapy.



Potassium-Sparing Diuretics

These drugs antagonize the effects of aldosterone at the cortical collecting tubule and late distal tubule.

Spironolactone inhibits the aldosterone receptor, while triamterene and amiloride appear to inhibit Na flux through ion channels in the lumenal membrane.

Hyperkalemia can result due to decreased K secretion.

Osmotic Diuretics



Acetazoamide acts on the proximal tubule.



Other Adverse Drug Reactions



Metabolic alkalosis


Altered calcuresis

Volume contraction