Hydroklorothiazid

Hydroklorothiazid, also spelled hydrochlorothiazide, is a thiazide-type diuretic used in the management of hypertension and edema. It works by inhibiting the sodium-chloride cotransporter in the distal convoluted tubule of the kidney, which reduces reabsorption of sodium and chloride and increases their excretion along with water. The resulting decrease in extracellular fluid volume contributes to lower blood pressure over several weeks. It is commonly prescribed in combination with other antihypertensives.

The drug is usually taken by mouth and is well absorbed from the gastrointestinal tract. Onset of action occurs within a few hours, with peak effects typically in the first day of dosing. The plasma half-life is generally on the order of several hours, and the drug is cleared primarily by the kidneys. Hydrochlorothiazide is available in various tablet strengths and is marketed as a generic medication and under brand names such as Microzide and Esidrix in many countries.

Clinical uses extend beyond hypertension to include edema associated with heart failure, liver cirrhosis, and certain kidney disorders. It may also be used in selected cases of nephrogenic diabetes insipidus to reduce polyuria. Dosing is individualized and based on patient response, comorbidities, and concurrent medications.

Common adverse effects include electrolyte disturbances such as hypokalemia, hyponatremia, and hypomagnesemia, as well as dehydration, dizziness, and increased cholesterol and uric acid levels. Photosensitivity can occur. Contraindications include anuria and known hypersensitivity to thiazides or sulfonamide-derived drugs; caution is advised in gout, diabetes, kidney disease, and during pregnancy or lactation. Interaction with other antihypertensives, NSAIDs, lithium, and antidiabetic agents can affect efficacy and safety.