Hydrochlorotiazid

Hydrochlorotiazid, more commonly spelled hydrochlorothiazide, is a thiazide diuretic used to treat high blood pressure and fluid retention from conditions such as heart failure, liver cirrhosis, or certain kidney disorders. It exerts its effect by inhibiting the sodium-chloride cotransporter in the distal convoluted tubule of the nephron. This reduces reabsorption of sodium and chloride, increasing their excretion along with water, which lowers blood volume and, over time, decreases vascular resistance.

Indications include essential hypertension, edema associated with heart failure or hepatic cirrhosis, and sometimes nephrotic syndrome. It may also be used to prevent calcium-containing kidney stones in idiopathic hypercalciuria, reflecting its effect on urinary calcium excretion. The drug is typically given orally, often once daily for hypertension, with dosing adjusted based on response and tolerability.

Pharmacokinetics for hydrochlorothiazide show good absorption after oral dosing, with peak plasma levels generally within a few hours. The elimination half-life is roughly 6 to 15 hours, and the drug is excreted largely unchanged in the urine.

Common adverse effects include electrolyte disturbances such as hypokalemia and hyponatremia, dehydration, and orthostatic hypotension. Hyperglycemia and elevated uric acid may occur, contributing to concerns for patients with diabetes or gout. Photosensitivity, dehydration, and allergic reactions are possible. Clinicians monitor blood pressure, electrolyte levels, and uric acid in patients taking hydrochlorothiazide, and caution is advised when coadministering with NSAIDs, lithium, or other antihypertensive agents. It is available in generic forms and under various brand names.