Agents that increase urine volume by altering ion transport in the nephron.

First line agents for hypertension and edematous states.

Five main classes: osmotic, carbonic anhydrase inhibitors, loop agents, thiazides and potassium spring agents.

Side effects include: volume depletion, hyperkalemia, hyponatremia, hyperglycemia and metabolic alkalosis.

Intravenous loop diuretics are adminstered in approximately 90% of patients hospitalized with heart failure.

High dose loop diuretics harmful effects include: activation of the renin-angiotensin and sympathetic nervous systems, electrolyte abnormalities and worsening renal function.

Loop diuretic exhibit their interaction in the thick ascending loop of Henle and include furosemide and bumetanide a short but powerful diuretic effect.

Loop diuretics include furosemide, butamide, torsemide and ethacrynic acid.

Loop diuretics are structurally similar, except for ethacrynic acid which lacks a sulfa moiety.

Ethacrynic acid has a greater risk of ototoxicity than other loop diuretics and its use is basically for patients with allergies to self.

In a prospective, randomized study of 308 patients with acute CHF receiving furosemide intravenously by either bolus every 12 hours or continuous infusion, and at low or high dose: no difference in patients’ global assessment of symptoms or in the change in renal function was noted by the type of adminstration (Felker GM et al).

Osmotic agents-mannitol and urea-increase tubular fluid osmolarity in entire tubule and may be associated wit hyponatremia.

Osmotic diuretics can decrease intraocular or intracranial pressure, increases water and metabolic toxin excretions with a lesser effect on sodium.

Osmotic diuretics can lead to dehydration and increased extra cellular fluid volume.

Carbonic anhydrase inhibitors-acetazolamide-affects proximal convoluted tubules and blocks Na+/H+ exchange.

Carbonic anhydrase inhibitors associated with hyperchloremic metabolic acidosis and hyperkalemia.

Carbonic anhydrase decreases bicarbonate and sodium reabsorption.

Thiazides such as hydrochlorothiazide and indapamide exert diuretic effects over a long period time in the distal convoluted tubule.

Potassium sparing diuretics such as triamterene and amiloride exert a weak diuretic effect but prevent potassium wasting.

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