Chlorthalidone (Edarbyclor, Tenoretic, Thalitone)

Overview

Chlorthalidone is a diuretic used to treat hypertension or edema caused by heart failure, renal failure, hepatic cirrhosis, estrogen therapy, and other conditions.

Mechanism of Action

Chlorthalidone prevents reabsorption of sodium and chloride through inhibition of the Na+/Cl- symporter in the cortical diluting segment of the ascending limb of the loop of Henle. Reduction of sodium reabsorption subsequently reduces extracellular fluid and plasma volume via an osmotic, sodium-driven diuresis. By increasing the delivery of sodium to the distal renal tubule, Chlorthalidone indirectly increases potassium excretion via the sodium-potassium exchange mechanism. The exact mechanism of chlorthalidone's anti-hypertensive effect is under debate, however, it is thought that increased diuresis results in decreased plasma and extracellular fluid volume which therefore requires decreased cardiac output and overall lowers blood pressure. Chlorthalidone has also been shown to decrease platelet aggregation and vascular permeability, as well as promote angiogenesis in vitro, which is thought to be partly the result of reductions in carbonic anhydrase–dependent pathways. These pathways may play a role in chlorthalidone's cardiovascular risk reduction effects.

Indications

Chlorthalidone is indicated in the management of hypertension either as the sole therapeutic agent or to enhance the effect of other antihypertensive drugs in the more severe forms of hypertension. Chlorthalidone is indicated as adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy. Chlorthalidone has also been found useful in edema due to various forms of renal dysfunction, such as nephrotic syndrome, acute glomerulonephritis, and chronic renal failure.

• Calcium Nephrolithiasis
• Edema
• Hypertension