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How do loop diuretics work?
- Inhibits the reabsorption of Na and Cl in the ascending limb of the loop of Henle by interfering with the chloride-binding of the
- Na+/K+/2Cl- cotransport system, altering electrolyte transfer in the proximal tubule. Diuresis results from the increased urinary excretion
- of Na,CL, K, and H+.
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List some loop diuretics.
- furosimide
- ethacrynic acid
- torsemide
- bumetanide
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How does furosimide work?
- furosemide is a sulfonimide. furosemide increases the excretion of calcium, magnesium, bicarbonate, ammonium, and phosphate. The diuresis caused by furosemide can lead to increased aldosterone production, resulting in increased sodium resorption, and increased potassium and hydrogen excretion. Furosemide's effectiveness is independent of the acid-base status of the patient. Renal vasodilation occurs following administration of
- furosemide; renal vascular resistance decreases, and renal blood flow is enhanced. Reduced peripheral vascular resistance and increased
- peripheral venous capacitance also occur.
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Side effects of furosimide.
- Hypokalemia and/or hypochloremia
- Since furosemide can reduce the clearance of uric acid, patients
- with gout or hyperuricemia can have exacerbations of their disease.
- High doses and accumulation of furosemide may cause ototoxicity
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When would you use ethacrynic acid?
- Ethacrynic acid can be particularly useful in patients who are
- unresponsive to other diuretics or who have severe renal impairment.
- Despite this, ethacrynic acid is seldom used due to its greater risk of
- ototoxicity when compared to the other loop diuretics bumetanide and
- furosemide
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How does Ethacrynic Acid work?
- Ethacrynic acid produces greater diuresis and electrolyte loss than do
- other diuretics (except furosemide or bumetanide), and its
- effectiveness is independent of the acid-base status of the patient. It
- has little to no effect on renal blood flow or the glomerular
- filtration rate. Unlike other loop diuretics, ethacrynic acid contains a
- beta-unsaturated ketone moiety, and was originally synthesized to mimic
- the sulfhydryl reactivity of the mercurial diuretics. The increased
- propensity of ethacrynic acid to bind to renal protein sulfhydryl
- groups may contribute to its diuretic actions by inhibiting
- sulfhydryl-catalyzed enzyme systems. Ethacrynic acid is not an
- aldosterone antagonist, and it does not affect carbonic anhydrase
- activity.
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