Metolazone Pediatric Dose — Diuretics
Metolazone is a thiazide-like diuretic that acts primarily by inhibiting sodium reabsorption in the distal convoluted tubule, producing natriuresis and diuresis. It is used in pediatric patients to manage fluid overload associated with conditions such as heart failure, chronic kidney disease, and diuretic resistance. Its prolonged duration of action and synergistic effect when combined with loop diuretics make it a valuable agent in complex diuretic regimens.
Pediatric Dosing
- Weight <40 kg: 0.1–0.2 mg/kg/dose PO every 12 hours
- Weight >40 kg (adult dosing): 5–10 mg/day PO
For a representative 20 kg child: 20 kg × 0.1 mg/kg = 2 mg/dose (low end); 20 kg × 0.2 mg/kg = 4 mg/dose (high end), administered every 12 hours. Consult institutional protocol for maximum single-dose limits not specified in the source description.
Indications and Clinical Context
Metolazone is indicated in pediatric patients with fluid overload states, particularly when loop diuretics alone provide inadequate diuresis — a phenomenon known as diuretic resistance. It is commonly employed in children with congestive heart failure, nephrotic syndrome, or chronic kidney disease requiring augmented diuretic response. The combination of metolazone with a loop diuretic (sequential nephron blockade) targets both the distal tubule and the loop of Henle, substantially enhancing urinary sodium and water excretion.
Its use in the inpatient and outpatient pediatric setting is guided by clinical response and electrolyte monitoring, and it is generally reserved for patients with refractory fluid retention or those transitioning between diuretic regimens under specialist supervision.
Administration and Monitoring
Metolazone is administered orally (PO); no parenteral formulation is available. When used in combination with a loop diuretic, it is typically given 30–60 minutes prior to the loop diuretic dose to maximize synergistic effect. Electrolyte monitoring — particularly serum potassium, sodium, magnesium, and bicarbonate — is essential given the risk of significant hypokalemia, hyponatremia, and metabolic alkalosis, especially with concurrent loop diuretic therapy.
- Monitor fluid balance closely; risk of over-diuresis and prerenal azotemia
- Check renal function (BUN, creatinine) periodically during therapy
- Use with caution in patients with hepatic impairment or known sulfonamide hypersensitivity
- Dose adjustments should be guided by clinical response and electrolyte status; consult institutional protocol for frequency of laboratory monitoring
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.