Metolazone

Administration

• Type: Diuretic, Thiazide-like
• Dosage Forms: Tablets (2.5mg, 5mg, 10mg)
• Routes of Administration: PO
• Common Trade Names: Zaroxolyn

Adult Dosing

General

• Edema: 2.5-10mg PO daily
• Hypertension: 2.5-5mg PO daily

Indications by Condition

Indication	Dose	Context	Route	Population
Volume overload	2.5-5mg PO 30min before loop diuretic	Thiazide added for diuretic resistance	PO	Adult

Pediatric Dosing

General

• 0.2-0.4mg/kg/day PO divided q12-24h

Special Populations

• Pregnancy Rating: B
• Lactation risk: Enters breast milk

Renal Dosing

• Effective even in renal impairment (unlike most thiazides)

Hepatic Dosing

• Use caution in hepatic impairment

Contraindications

• Allergy to class/drug
• Anuria
• Hepatic coma

Adverse Drug Reactions

Serious

• Hypokalemia
• Hyponatremia
• Metabolic alkalosis

Common

• Dizziness
• Headache
• Muscle cramps

Pharmacology

• Onset of action: 1 hour
• Half-life: 14 hours
• Metabolism: Minimal hepatic
• Excretion: Renal (80%)

Mechanism of Action

• Inhibits sodium reabsorption in the distal convoluted tubule
• Synergistic with loop diuretics for diuretic resistance

See Also

• Loop diuretic
• Volume overload
• Congestive heart failure