Dosing and uses of Zaroxolyn (metolazone)
Adult dosage forms and strengths
tablet
- 2.5mg
- 5mg
- 10mg
Hypertension
2.5-5 mg PO once daily; may be increased to 20 mg once daily PRn
Edema
2.5-10 mg PO once daily initially; may be gradually increased to 20 mg once daily
Dosing Modifications
Renal impairment: Not necessary to supplement dose in hemodialysis or peritoneal dialysis
Dosing Considerations
Overdose management
- Normal saline may be used for volume replacement
- Dopamine or norepinephrine may be used to treat hypotension
- Discontinue treatment if no symptoms are apparent after 6 hours
Pediatric dosage forms and strengths
tablet
- 2.5mg
- 5mg
- 10mg
Edema (Off-label)
0.2-0.4 mg/kg/day PO in single daily dose or divided q12hr
Geriatric dosage forms and strengths
Increased risk of azotemia and electrolyte depletion when used in combination with diuretics in elderly
Edema
2.5 mg PO once daily or every other day
Zaroxolyn (metolazone) adverse (side) effects
Frequency not defined
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
Warnings
Contraindications
Documented hypersensitivity to metolazone or sulfonamides
Anuria
Hepatic coma or precoma
Cautions
Use with caution in diabetes mellitus, fluid or electrolyte imbalance, hypercholesterolemia, hyperuricemia or gout, hypotension, systemic lupus erythematosus, previous sympathectomy, liver disease, renal disease
Avoid concurrent use with lithium (reduction of lithium dosage by 50% may be necessary)
May aggravate digitalis toxicity
Photosensitization may occur
Electrolyte disturbances (eg, hyponatremia, hypochloremic alkalosis) may occur
Sensitivity reactions may occur with or without history of allergy or asthma
Patients allergic to sulfa may show cross-sensitivity
May deleteriously alter lipid/glucose metabolism
Mykrox not therapeutically interchangeable with Zaroxolyn
Risk of male sexual dysfunction
Pregnancy and lactation
Pregnancy category: B
Lactation: Not recommended
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Zaroxolyn (metolazone)
Mechanism of action
Inhibits reabsorption of sodium in distal tubules, causing increased excretion of water and of sodium, potassium, and hydrogen ions
Absorption
Bioavailability: 40-65%
Onset: Diuresis, 1 hr
Duration: 24 hr
Peak plasma time: Zaroxolyn, 8 hr
Distribution
Protein bound: 95%
Metabolism
Minimally metabolized; site of metabolism unspecified
Elimination
Half-life: 20 hr
Dialyzable: Hemodialysis, no
Excretion: Urine (80%), bile (10%)
