Metolazone
ZAROXOLYN
What it isNCC-inhibiting thiazide-like diuretic; refractory edema in heart failure and kidney disease.
Why this oneIts pronounced synergy with loop diuretics makes it a rescue for diuretic-resistant edema even at low GFR.
What limits itThe combined diuresis can be profound — check electrolytes and volume within days. It is not interchangeable with other thiazides.
FDA-approved for
- edema (~1974)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Edema of cardiac failure | Adult | 5–20 mg QD | ||
| Edema of renal disease | Adult | 5–20 mg QD | ||
| Mild–moderate essential hypertension | Adult | 2.5–5 mg QD |
Renal Undefined (contraindicated in anuria)
Hepatic Undefined (contraindicated in hepatic coma/precoma)
Instructions
- Single daily dose; titrate to the minimal effective dose
- Reduce dose once desired therapeutic effect obtained
Contraindications
- Anuria
- Hepatic coma or precoma
Cautions
- Electrolyte imbalance: hypokalemia, hyponatremia, hypochloremic alkalosis
- Excessive volume depletion / orthostatic hypotension
- Hyperuricemia (gout), hyperglycemia
- Serious skin reactions (TEN, Stevens-Johnson syndrome)
- Photosensitivity
Adverse reactions
- Orthostatic hypotension
- Volume depletion
- Hypokalemia, hyponatremia
- Hyperuricemia
- Dizziness/lightheadedness
- Headache
- Muscle cramps
Pregnancy Use only if clearly needed; crosses placenta; risk of fetal/neonatal jaundice and thrombocytopenia
Lactation Undefined
⚠ BOXED WARNING
- Potent diuretic; not interchangeable with other thiazides
Principal riskProfound diuresis and electrolyte loss when added to a loop diuretic
Cost, est. cash$5–$150/month
Generic entry2003
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityVolume depletion and electrolyte disturbances; kidney function and interacting medications modify risk.
Mechanism of action: Metolazone ballicule
Open Metolazone in the interactive console ↗
Memory aids: mascots and interaction avatars
Bananas dispersing → ↓ serum potassium
