What is the equivalent dose of Bumex (bumetanide) for a patient taking Lasix (furosemide) 80 mg Intravenous (IV)?

Equivalent Dose of Bumex for Lasix 80 mg IV

The equivalent dose of bumetanide (Bumex) for furosemide (Lasix) 80 mg IV is 2 mg IV. 1, 2

Conversion Rationale

The conversion between IV furosemide and IV bumetanide follows a well-established ratio:

• The standard conversion ratio is 40:1 (furosemide:bumetanide) for IV administration 3
• Therefore, 80 mg IV furosemide = 2 mg IV bumetanide

This conversion is supported by multiple guidelines and pharmacological evidence:

• The European Society of Cardiology guidelines specifically mention that 20-40 mg IV furosemide is equivalent to 0.5-1 mg IV bumetanide 1
• Pharmacological studies consistently demonstrate that bumetanide is approximately 40 times more potent than furosemide in terms of natriuretic effect 3, 4

Clinical Considerations

When converting between these loop diuretics, consider these important factors:

• Onset of action: Both medications have similar rapid onset when given IV (within 30 minutes) 3
• Duration of effect: Both medications have similar duration of action (3-6 hours) 3
• Potency differences: While bumetanide is 40 times more potent for sodium excretion, its potency for potassium excretion is proportionally lower 3
• Bioavailability: For oral dosing, the conversion would be different due to differences in oral bioavailability (not applicable to this IV-to-IV conversion) 5

Monitoring Recommendations

After conversion, monitor:

• Urine output
• Vital signs (especially blood pressure, avoiding SBP <90 mmHg)
• Electrolytes (particularly potassium and sodium)
• Acid-base balance
• Signs of dehydration or continued fluid overload 2

Common Pitfalls to Avoid

1. Assuming equal potency for all electrolyte effects: While the 40:1 ratio applies to natriuretic effects, bumetanide has proportionally less effect on potassium excretion 3

2. Applying IV conversion ratios to oral dosing: The oral bioavailability differs between these medications, so different conversion ratios apply for oral administration 6

3. Overlooking patient-specific factors: Patients with renal insufficiency may respond differently to each medication, with some studies showing furosemide might produce greater cumulative natriuresis in severe renal insufficiency despite equal maximal fractional sodium excretion 4

4. Inadequate monitoring: Both medications can cause similar adverse effects including electrolyte abnormalities and hypotension, requiring careful monitoring 2