thiazider

Thiazide diuretics, sometimes referred to as thiaziders, are a class of diuretics used to treat hypertension and various forms of edema. They act on the distal convoluted tubule of the nephron, where they inhibit the sodium-chloride cotransporter, leading to increased excretion of sodium, chloride, and water. They are often distinguished from loop diuretics and potassium-sparing diuretics by their site of action and milder diuretic effect but longer duration of action.

The primary pharmacologic effect is natriuresis with a relatively modest increase in urine output, but this action persists for many hours. In addition to lowering blood pressure, thiazides reduce urinary calcium excretion, which can be beneficial for some patients with idiopathic hypercalciuria. Common agents in this class include hydrochlorothiazide, chlorthalidone, indapamide, and metolazone (often grouped with thiazides though some are pharmacologically distinct). Thiazides are typically given orally and have a duration of action that supports once-daily dosing for many indications.

Indications for thiazide use include essential hypertension, edema associated with heart failure or cirrhosis, and certain kidney stone disorders. They are also used in the management of nephrogenic diabetes insipidus to reduce polyuria in some cases. They are frequently used in combination with other antihypertensives such as ACE inhibitors or ARBs.

Common adverse effects include hyponatremia, hypokalemia, dehydration, and hyperuricemia, which can provoke gout. They may impair glucose tolerance and raise blood sugar modestly. Caution is advised in patients with renal impairment, gout, or a history of hyponatremia, and NSAID use can diminish their antihypertensive effect. Monitoring of electrolytes, uric acid, and glucose is recommended during therapy.