Metolazone

Metolazone is a thiazide-like diuretic used to reduce fluid buildup and to help control blood pressure. It is commonly prescribed for edema associated with congestive heart failure, liver cirrhosis, and nephrotic syndrome, and can be used as an adjunct in hypertensive patients. It is often selected for patients with diuretic-resistant edema when another loop diuretic is not producing adequate relief.

Pharmacology and mechanism: Metolazone inhibits the Na-Cl cotransporter in the distal convoluted tubule of the kidney, leading to increased excretion of sodium and water. It is generally effective even when kidney function is reduced more than other thiazides. After oral administration, onset of diuretic effect occurs within about 1 to 2 hours, with peak effects in a few hours and a duration that can range from about 24 to 72 hours.

Administration and typical use: Metolazone is taken orally in tablet form and may be used alone or in combination with loop diuretics to overcome diuretic resistance in conditions such as heart failure. Dose and frequency depend on the condition being treated and patient response. Caution is advised in patients with electrolyte disturbances or reduced renal function, and adjustments may be necessary in renal impairment.

Adverse effects and cautions: Common issues include electrolyte disturbances (hypokalemia, hyponatremia, and hypomagnesemia), dehydration, and hyperglycemia in susceptible individuals. Gout may be precipitated or worsened due to hyperuricemia. Photosensitivity and interactions with other antihypertensives, nonsteroidal anti-inflammatory drugs, and lithium can occur. Metolazone should be used during pregnancy only if clearly needed and under medical supervision.