Metolazone

DEA Class; Rx

Common Brand Names; Zaroxolyn

• Diuretics, Other

Oral quinazoline diuretic; used for edema and HTN; sulfonamide derivative; may produce diuresis in patients with impaired renal function; Zaroxolyn® is a formulation with relatively slow and incomplete absorption. Mykrox®, a more rapidly absorbed product with enhanced bioavailability, is no longer available in the US.

Indicated for the treatment of hypertension.

Documented hypersensitivity to metolazone or sulfonamides

Anuria

Hepatic coma or precoma

• Chest pain
• Depression
• Dizziness
• Drowsiness
• Electrolyte abnormalities
• Glucosuria
• Gout attacks
• Headache
• Hemoconcentration
• Hepatotoxicity
• Hyperuricemia
• Hypochloremic alkalosis
• Hypokalemia
• Hypomagnesemia
• Hyponatremia
• Hypophosphatemia
• Hyperglycemia
• Hypercalcemia
• Impotence
• Increased blood urea nitrogen (BUN)
• Joint pain
• Leukopenia
• Lightheadedness
• Necrotizing angiitis
• Neuropathy
• Nocturia
• Orthostatic hypotension
• Palpitations
• Pancreatitis
• Restlessness
• Stevens-Johnson syndrome
• Syncope
• Toxic epidermal necrolysis
• Urticaria
• Venous thrombosis
• Volume depletion

Use with caution in diabetes mellitus, hypercholesterolemia, hyperuricemia or gout, hypotension, systemic lupus erythematosus (can cause exacerbation or activation), previous sympathectomy, liver disease

Avoid concurrent use with lithium (reduction of lithium dosage by 50% may be necessary)

May aggravate digitalis toxicity

Photosensitization may occur

Severe hypokalemia and/or hyponatremia may occur following initial doses; hypochloremic alkalosis, hypercalcemia, and/or hypomagnesemia may also occur; correct electrolyte imbalance before initiating therapy

Angioedema and other hypersensitivity reactions may occur, including bronchospasm with or without history of allergy or asthma

Patients allergic to sulfa may show cross-sensitivity; however, recent studies on allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur or, at the very least, this potential is extremely low

May deleteriously alter lipid/glucose metabolism

Mykrox not therapeutically interchangeable with Zaroxolyn

Risk of male sexual dysfunction

Monitor for hypotension if administered concurrently with hypotensive agents

If azotemia and oliguria worsen during treatment in patients with renal disease, discontinue therapy

In primary adrenal insufficiency, avoid use of diuretics to treat hypertension; adjustment of glucocorticoid/mineralocorticoid therapy and/or use of other antihepertensive agents preferred

Therapy with metolazone may render the patients volume depleted if given in the morning of surgery; blood pressure may be labile during general anesthesia

Pregnancy

Drug appears in cord blood and crosses placenta; hypokalemia, hypoglycemia, jaundice, thrombocytopenia, and hyponatremia reported in fetus or newborn following maternal use of thiazide diuretics

Lactation

Drug excreted in breast milk; decision on whether to discontinue nursing or discontinue drug should be based on importance of treatment to mother