Bumetanide

Mechanism

Pharmacological Group

Loop diuretic derived from sulfamoyl metanylamide.

Mechanism of Action

Like furosemide, it inhibits electrolyte reabsorption in Henle's RAG by competitively blocking the apical NKCC2 cotransporter. Its molar potency is 40 to 50 times greater than that of furosemide, requiring substantially lower concentrations in plasma and tubular lumen to achieve an equivalent response.

Pharmacokinetics

Key Pharmacokinetics

• Absorption: Rapid and almost complete in the digestive tract.
• Bioavailability: 80-95% (very predictable compared to furosemide). It is not significantly altered by concomitant food intake or visceral congestion of IC.
• Metabolism: Hepatic oxidation of the butyl side chain to 50% inactive metabolites.
• Excretion: 50% by unaltered renal excretion via tubular secretion; the rest is eliminated through bile and hepatic metabolism.
• Half-life: 1 to 1.5 hours.

Indicators and dose

Clinical Indications

• Refractory edema of cardiac, hepatic or renal cause: Of choice when there is resistance or poor response to furosemide due to absorption problems.
• Substitution treatment in patients with intestinal wall edema: Due to its predictable absorption profile.

Dosage and Settings

• Adults: 0.5 mg to 2 mg daily orally; It can be repeated after 4-5 hours if diuresis is insufficient. Maximum recommended daily dose: 10 mg.
• Liver Failure: Use with strict caution. Maintain minimum effective doses to prevent sudden drops in potassium and ammonium that precipitate encephalopathy.

Security

Contraindications

Identical to furosemide. Hepatic encephalopathy and established anuria.

Adverse Effects (ADR)

• Common: Muscle cramps (due to hypokalemia), hypochloremic alkalosis, dehydration, dizziness, postural hypotension.
• Differential safety: Lower relative incidence of ototoxicity reported compared to infusions of equivalent doses of furosemide.

Interactions

Toxic synergy with ototoxic drugs (aminoglycosides, cisplatin) and nephrotic drugs. Decreased effect due to NSAIDs.

Pregnancy and Breastfeeding

Category C. Not recommended during pregnancy. Use only if the clinical benefit justifies the potential fetal risk.

Clinical

Clinical Equivalences Clinical

A highly useful tool for rapid switching of loop diuretics in daily practice:

Bumetanide
1 mg ≈ Torasemide
10 to 20 mg ≈ Furosemide IV
20 to 40 mg ≈ Furosemide PO
40 to 80 mg