How to convert Bumex (bumetanide) 1mg IV to oral dosage?

Converting Bumetanide from IV to Oral Dosing

When converting bumetanide 1mg IV twice daily to oral dosing, use a 1:1 conversion ratio with the same total daily dose of 2mg, administered as bumetanide 1mg orally twice daily.

Rationale for Conversion

Bumetanide is a potent loop diuretic used primarily in the treatment of fluid retention associated with heart failure. When converting from IV to oral administration, several pharmacokinetic properties must be considered:

• Bumetanide has approximately 80-100% oral bioavailability 1
• Unlike furosemide, which has variable absorption, bumetanide has consistent and reliable oral absorption 2
• The pharmacokinetic profiles of oral and parenteral bumetanide are similar 3

Dosing Guidelines

According to the ACC/AHA guidelines for heart failure management, the recommended dosing for bumetanide is:

• Initial daily dose: 0.5 to 1.0 mg once or twice daily
• Maximum daily dose: 10 mg
• Duration of action: 4 to 6 hours 4

Conversion Protocol

1. Identify current IV dose: 1mg IV twice daily (total 2mg daily)
2. Apply 1:1 conversion ratio
3. Convert to: 1mg oral twice daily (total 2mg daily)

Clinical Considerations

• Timing: Maintain the same dosing interval (twice daily) to ensure consistent diuretic effect throughout the day
• Monitoring: After conversion, monitor:
  • Daily weight
  • Urine output
  • Electrolytes (particularly potassium)
  • Renal function
• Dose Adjustment: The ultimate goal of diuretic treatment is to eliminate clinical evidence of fluid retention. Further increases in dose or frequency may be required to maintain active diuresis and sustain weight loss 4

Special Populations

• Elderly patients: Total bumetanide clearance may be significantly lower in geriatric patients. Consider monitoring more closely after conversion 5
• Renal impairment: Patients with renal insufficiency may require higher doses but should be monitored closely for adverse effects 3

Common Pitfalls to Avoid

1. Assuming different bioavailability: Unlike furosemide, which has significantly lower oral bioavailability compared to IV administration, bumetanide has high oral bioavailability (approximately 80-100%), allowing for a 1:1 conversion 2, 1

2. Inadequate monitoring: After conversion, patients should be monitored for changes in diuretic response, as individual variations may occur

3. Failure to adjust sodium intake: Dietary sodium restriction (to <2.0 g/d) should accompany diuretic therapy for optimal effect 4

Remember that diuretics should generally be combined with other guideline-directed medical therapy for heart failure, such as ACE inhibitors, beta-blockers, and aldosterone antagonists when appropriate 4.