Thiazidien

Thiazidien, in English thiazide diuretics, are a class of medications used primarily to treat hypertension and edema. They act on the kidney’s distal convoluted tubule, where they inhibit the sodium-chloride cotransporter (NCC). This reduces sodium and chloride reabsorption, increasing their excretion and promoting diuresis. The effect is modestly accompanied by a rise in potassium excretion, and thiazides can also increase calcium reabsorption, which can influence calcium balance.

Common thiazide agents include hydrochlorothiazide, chlorthalidone, indapamide, and metolazone. Some are considered thiazide-like diuretics due to differences in potency, duration of action, and pharmacokinetics. Hydrochlorothiazide is a short- to intermediate-acting agent, while chlorthalidone has a longer duration and has shown cardiovascular benefits in some trials. Indapamide and metolazone offer additional hemodynamic or potency characteristics.

Clinical uses of thiazides include first-line or add-on therapy for essential hypertension, treatment of edema from heart failure, hepatic cirrhosis, and nephrotic syndrome, and, in some cases, prevention of calcium-containing kidney stones. They may also be used to reduce polyuria in nephrogenic diabetes insipidus. In patients with reduced kidney function (e.g., low glomerular filtration rate), thiazides become less effective; metolazone can be used in combination with loop diuretics in certain cases.

Adverse effects and considerations include electrolyte disturbances (notably hyponatremia and hypokalemia), dehydration, and possible hyperglycemia or impaired glucose tolerance. Thiazides can raise uric acid levels, increasing gout risk. They may interact with nonsteroidal anti-inflammatory drugs and with agents that affect potassium balance. Use is generally avoided in severe electrolyte disturbances or anuria, and caution is advised in pregnancy and in patients with diabetes or gout.

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