handlingthiazides

Thiazide diuretics are a class of medications used primarily to treat hypertension and edema. They act by inhibiting the sodium-chloride symporter in the distal convoluted tubule of the nephron, increasing excretion of sodium and water, and over time reducing peripheral vascular resistance.

Common agents include hydrochlorothiazide, chlorthalidone, indapamide, and metolazone. Chlorthalidone has a longer duration of action and is frequently associated with favorable cardiovascular outcome data; indapamide has additional vasodilatory properties; metolazone is more potent and can be useful in resistant edema or when kidney function is reduced.

Indications cover essential hypertension and edema due to heart failure, cirrhosis, or nephrotic syndrome. They may also help prevent calcium-containing kidney stones due to increased calcium reabsorption in the distal tubule.

Dosing is individualized and typically started at low doses, then titrated to effect while monitoring safety. Examples include hydrochlorothiazide 12.5–25 mg daily, chlorthalidone 12.5–25 mg daily, indapamide 1.25–2.5 mg daily, and metolazone 2.5–5 mg as needed. Dosing adjustments depend on response and comorbid conditions.

Contraindications include anuria and severe renal impairment; caution with known sulfonamide sensitivity; gout. In pregnancy and lactation, use is limited and alternatives are often preferred.

Adverse effects comprise hyponatremia, hypokalemia, dehydration, and hyperuricemia, with possible mild hyperglycemia and photosensitivity. Interactions include reduced diuretic effect with NSAIDs, potential potassium imbalances with other agents, and increased lithium toxicity risk.

Monitoring should include baseline and periodic electrolyte panels, renal function, uric acid, glucose, and blood pressure. Thiazides are less effective when glomerular filtration rate is very low; metolazone may still be useful in such cases.