Diuretics mainly exert their effect by the inhibition of renal tubular reabsorption of sodium and water. These may be classified according to ◆ their efficacy as ● high ceiling (loop and osmotic diuretics), ● medium ceiling (thiazides) and ● low ceiling (carbonic anhydrase inhibitors ● potassium sparing) diuretics. ◆ based on their site of action 1. Diuretics Acting on the Proximal Tubule (Pt) These are non-competitive but reversible inhibitors of carbonic anhydrase and act by inhibiting the reabsorption of sodium in the proximal tubular portion of the nephron. ● Carbonic Anhydrase (CA) Inhibitors net effect of carbonic anhydrase is to cause the absorption of sodium and bicarbonate. (acetazolamide, dichlorphenamide and methazolamide) 2. Diuretics Acting on the Loop of Henle ● Inhibitors of Na+-K+-ATPase loop diuretics and act by causing inhibition of Na+ K+ 2Cl–symporter present at the luminal membrane of the ascending limb of loop of Henle. (Furosemide, torsemide, bumetanide, ethacrynic acid, axosemide, piretanide, tripamide and mersaly) ● Osmotic Diuretics Mannitol, glycerol, urea and isosorbide are inert drugs that can cause osmotic diuresis. these drugs act both in PT as well as loop of Henle,
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