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Thiazide-Like Diuretic

Metolazone

Brand names: Metenix (discontinued in UK), metolazone (imported/special)

Metolazone is a thiazide-like diuretic used mainly in addition to a loop diuretic to produce powerful synergistic diuresis in resistant oedema and heart failure.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION Effective dosage of metolazone tablets should be individualized according to indication and patient response. A single daily dose is recommended. Therapy with metolazone tablets should be titrated to gain an initial therapeutic response and to determine the minimal dose possible to maintain the desired therapeutic response. Usual Single Daily Dosage Schedules Suitable initial dosages will usually fall in the ranges given. Edema of cardiac failure: Metolazone tablets, 5 mg to 20 mg once daily. Edema of renal disease: Metolazone tablets, 5 mg to 20 mg once daily. Mild to moderate essential hypertension: Metolazone tablets, 2.5 mg to 5 mg once daily. New patients - If …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-12-24. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It inhibits sodium-chloride reabsorption in the distal convoluted tubule; combined with loop diuretic blockade more proximally, this sequential nephron blockade drives a profuse diuresis.

Prescribing in practice

  • When added to a loop diuretic the diuresis can be profound—monitor closely for hypokalaemia, hypovolaemia, hypotension and worsening renal function.
  • Use is generally specialist-supervised, often intermittently rather than continuously, with frequent review of weight, electrolytes and fluid status.
  • Check renal function and electrolytes before and during treatment, and correct potassium as needed.

Monitoring

Monitor renal function, electrolytes (especially potassium and sodium), blood pressure, weight and fluid status frequently during combined diuretic therapy.

Counselling the patient

  • You may pass a large amount of urine—follow the agreed schedule and attend the planned blood tests and weight checks.
  • Report marked dizziness, severe weakness, muscle cramps or significantly reduced urine output promptly.

Evidence & guidelines

Established adjunct to loop diuretics for diuretic-resistant oedema in heart failure (NICE NG106).

Reference: ESC Heart Failure Guidelines 2021; AHA/ACC HF Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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