Bumex - Drug Monograph

Introduction

Bumex (bumetanide) is a potent loop diuretic medication used primarily for the management of edema associated with congestive heart failure, hepatic cirrhosis, and renal disease. As a sulfonamide derivative, it shares pharmacological similarities with furosemide but demonstrates approximately 40 times greater potency on a milligram-to-milligram basis. Bumetanide was approved by the FDA in 1983 and remains an important therapeutic option in fluid overload states.

Mechanism of Action

Bumetanide exerts its diuretic effect by specifically inhibiting the sodium-potassium-chloride (Na⁺-K⁺-2Cl⁻) cotransporter in the thick ascending limb of the loop of Henle. This inhibition reduces the reabsorption of sodium and chloride ions, creating an osmotic gradient that prevents water reabsorption. The resulting increased excretion of sodium, chloride, and water produces profound diuresis. Additionally, bumetanide promotes excretion of calcium, magnesium, and potassium ions.

Indications

FDA-approved indications include:

• Edema associated with congestive heart failure
• Edema associated with hepatic cirrhosis
• Edema associated with renal disease, including nephrotic syndrome

Off-label uses include:

• Hypertension (particularly when thiazides are ineffective)
• Hypercalcemia
• Ascites
• Acute pulmonary edema

Dosage and Administration

• Initial dose: 0.5-2 mg once daily
• Maintenance dose: 0.5-6 mg daily (maximum 10 mg daily)
• May be given as single dose or divided doses

• IV/IM: 0.5-1 mg, may repeat every 2-3 hours
• Maximum IV dose: 10 mg daily

• Renal impairment: No specific dosage adjustment required
• Hepatic impairment: Use with caution due to electrolyte imbalance risk
• Geriatric patients: Start with lower doses due to increased sensitivity
• Pediatric patients: 0.015-0.1 mg/kg/dose (maximum 10 mg daily)

Pharmacokinetics

Contraindications

• Hypersensitivity to bumetanide or sulfonamides
• Anuria
• Hepatic coma or severe electrolyte depletion
• Patients in whom diuresis is inappropriate

Warnings and Precautions

• Bumetanide is a potent diuretic that can lead to profound diuresis with water and electrolyte depletion
• Close medical supervision required, especially during initial therapy

• Ototoxicity risk (especially with rapid IV administration or concurrent ototoxic drugs)
• Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia)
• Hyperuricemia and gout exacerbation
• Photosensitivity reactions
• Orthostatic hypotension
• Use in pregnancy (Category C) and lactation

Drug Interactions

• Aminoglycosides: Increased risk of ototoxicity and nephrotoxicity
• Digoxin: Hypokalemia may potentiate digitalis toxicity
• Lithium: Reduced renal clearance leading to lithium toxicity
• Probenecid: Reduced diuretic effect
• NSAIDs: Reduced diuretic and antihypertensive effects
• Antihypertensive agents: Potentiated hypotensive effects
• Corticosteroids: Enhanced potassium wasting

Adverse Effects

• Dehydration (15-20%)
• Hypokalemia (15-20%)
• Hyponatremia (5-10%)
• Headache (5-10%)
• Dizziness (5-8%)
• Muscle cramps (3-5%)
• Nausea (2-4%)

• Ototoxicity (dose-related)
• Stevens-Johnson syndrome
• Thrombocytopenia
• Neutropenia
• Aplastic anemia
• Anaphylactic reactions
• Acute pancreatitis
• Hepatic encephalopathy

Monitoring Parameters

• Complete metabolic panel (electrolytes, BUN, creatinine)
• Liver function tests
• Urinalysis
• Weight and fluid status assessment
• Blood pressure

• Serum electrolytes (especially potassium) every 1-3 months
• Renal function periodically
• Daily weights
• Blood pressure
• Hearing assessment with high doses or prolonged therapy
• Signs of dehydration or volume depletion

Patient Education

• Take medication in morning to avoid nighttime diuresis
• Report signs of electrolyte imbalance (muscle cramps, weakness, dizziness)
• Monitor weight daily at same time with same scale
• Maintain consistent potassium intake as recommended
• Rise slowly from sitting/lying position to prevent dizziness
• Use sun protection due to photosensitivity risk
• Report hearing changes or ringing in ears immediately
• Avoid NSAIDs unless specifically approved by physician
• Understand expected increase in urinary frequency

References

1. FDA Prescribing Information: Bumex (bumetanide) tablets and injection 2. Brunton LL, Hilal-Dandan R, Knollmann BC. Goodman & Gilman's: The Pharmacological Basis of Therapeutics. 13th ed. 2017 3. Lexicomp Online: Bumetanide monograph 4. Ellison DH. Clinical Pharmacology of Loop Diuretics. In: UpToDate, 2023 5. Sica DA. Pharmacokinetics and Pharmacodynamics of Loop Diuretics in Heart Failure. Heart Fail Rev. 2021;26(3):623-636 6. Oh SW, Han SY. Loop Diuretics in Clinical Practice. Electrolyte Blood Press. 2015;13(1):17-21 7. National Kidney Foundation. KDOQI Clinical Practice Guideline for Hypertension and Antihypertensive Agents in Chronic Kidney Disease. Am J Kidney Dis. 2004;43(5 Suppl 1):S1-290