klortalidon

Klortalidon, internationally known as chlorthalidone, is a thiazide-like diuretic used to treat hypertension and edema associated with heart failure, liver cirrhosis, and nephrotic syndrome. It is often chosen for hypertension because of its long duration of action and evidence of cardiovascular risk reduction in some trials.

Its mechanism of action is inhibition of the sodium-chloride cotransporter in the distal convoluted tubule of the nephron. This results in increased excretion of sodium and chloride with accompanying water, and a tendency toward potassium loss.

Chlorthalidone is taken orally. It is absorbed from the gastrointestinal tract and has a long plasma half-life, allowing once-daily dosing. It is largely excreted by the kidneys, with some metabolism. Onset of diuresis is typically within hours, with sustained effect over 24 hours or more.

Common adverse effects include electrolyte disturbances such as hypokalemia and hyponatremia, dehydration, and hyperuricemia which can precipitate gout. Photosensitivity, dizziness, and fatigue may occur. It can interact with nonsteroidal anti-inflammatory drugs, lithium, and other antihypertensives, potentially increasing adverse effects or reducing efficacy.

Contraindications include severe kidney failure with little or no urine production, anuria, and a history of hypersensitivity to sulfonamides. It should be used with caution in gout, kidney disease, and pregnancy. As with other diuretics, monitoring of electrolytes, uric acid, and kidney function is recommended.