Low-ceiling diuretics

The most popular diuretics in this class are hydrochlorothiazide and chlorthalidone there arc more potent low ceiling diuretics available. The long duration of action of chlorthalidone, 24 to 72 h, makes once a day dosing possible, and achieves good patient compliance. Cyclolhiazide, polythia/ide. and irichlunnethiazide are about 15 to 30 limes more potent than hydrochlorothiazide, and about 500 to 1000 times more potent than chlorothiazide, flic first member of the thiazide family marketed. 

The low ceiling diuretics increase urinary sodium excretion by acting directly on the Na - Cl transport mechanism in rhe convoluted distal lubttles of the kidney. 

Xipamide is classed as a low-ceiling diuretic with its effective dynamics and intensity ranking between furo-semide and the thiazides. For this reason, there are no extreme peaks of diuresis during prolonged therapy. Calciuria is typical for loop diuretics. With portal ascites, xipamide has proved to be almost diuretically equivalent to spironolactone. 

Four additional high-ceiling diuretics are azosemide, muzolimine, piretanide, and tripamide. Azosemide has low oral bioavailability (-10-15%) because of high first-pass metabolism in the liver, whereas piretanide has comparable pharmacokinetics to bumetanide. 

Ascites. Patients with cirrhosis, especially fiver cirrhosis, very often develop ascites, ie, accumulation of fluid in the peritoneal cavity. This is the final event resulting from the hemodynamic disturbances in the systemic and splanchnic circulations that lead to sodium and water retention. When therapy with a low sodium diet fails, the dmg of choice for the treatment of ascites is furosemide, a high ceiling (loop) diuretic, or spironolactone, an aldosterone receptor antagonist/potassium-sparing diuretic. 

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