Loop diuretic
Bumetanide (Bumex)
Also called Bumex
Indications
- Edema from heart failure, cirrhosis or kidney disease, including nephrotic syndrome (label)
- Acute decompensated heart failure with congestion, by IV bolus or continuous infusion (infusion off-label)
- Diuretic resistance, since oral absorption is nearly complete, and furosemide allergy (label: successful use after furosemide reactions suggests little cross-sensitivity)
- Fluid overload in AKI or ARDS, managing volume without treating the AKI (off-label)
Dosing
Mechanism of action
Bumetanide blocks NKCC2, the luminal Na⁺-K⁺-2Cl⁻ cotransporter of the thick ascending limb, which reabsorbs about a quarter of filtered sodium. Highly protein-bound, it reaches the lumen by organic anion secretion in the proximal tubule, so its effect depends on delivery into the urine. Losing the lumen-positive voltage cuts Ca²⁺ and Mg²⁺ reabsorption, the medullary gradient washes out, and extra sodium reaching the collecting duct drives K⁺ and H⁺ loss. By weight it is about 40 times as potent as furosemide; it also blocks NKCC1, including in the inner ear.
Pharmacology
- Renal: natriuresis within minutes of an IV dose, peaking at 15–30 min (label); a weak response needs a higher dose, not a repeat
- Renal: urine loses K⁺, Mg²⁺, Ca²⁺, Cl⁻ and H⁺
- Metabolic: hyperuricemia 18.4%, hypochloremia 14.9%, hypokalemia 14.7% and hyponatremia 9.2% in label trials; contraction alkalosis
- Cardiovascular: preload and BP fall with volume loss; hypotension in under 1% (label)
- Musculoskeletal: muscle cramps in 1.1% (label)
- Ear: in animals 5–6 times as ototoxic as furosemide by weight (label), against about 40 times its diuretic potency
Pharmacokinetics
| Onset | IV within minutes; oral 30–60 min (labels) |
|---|---|
| Peak | IV 15–30 min; oral 1–2 h (labels) |
| Duration | Mostly complete within 4 h at 1–2 mg; 4–6 h with higher doses (label) |
| Half-life | 1–1.5 h in adults; about 6 h in neonates (label) |
| Protein binding | 94–96% (label) |
| Metabolism | Liver oxidation of the N-butyl side chain (label) |
| Elimination | Urine 81%, 45% as unchanged drug; bile 2% (label) |
| Bioavailability | Nearly complete orally, so oral and IV doses act alike (label) |
| Organ failure | Kidney failure: less drug reaches the tubule, so higher doses are needed. Liver failure: keep doses low; older adults clear it more slowly (label) |
Chemistry
- 3-(butylamino)-4-phenoxy-5-sulfamoylbenzoic acid (C₁₇H₂₀N₂O₅S, MW 364.4): a sulfamoylbenzoic acid like furosemide, with phenoxy and butylamino groups
- Weak acid, carboxyl pKa about 3.6–3.8 (PubChem): fully ionized at pH 7.4, which keeps it in plasma and lets organic anion transporters secrete it
- Injection 0.25 mg/mL with sodium chloride, ammonium acetate, edetate and benzyl alcohol, pH 6.8–7.8 (label)
- Light-sensitive: protect from light; use diluted solutions within 24 h (label)
Adverse effects and cautions
Other loop diuretic drugs
Sources
- FDA label: Bumetanide Injection (Hikma, 2023)
- FDA label: Bumetanide tablets (2025)
- Brater 1998 (diuretic therapy)
- PubChem: bumetanide
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.