Amphotericin B Deoxycholate Dilution Volume
160 mg of amphotericin B deoxycholate should be dissolved in sufficient 5% dextrose to achieve a final concentration of 0.1 mg/mL, which requires 1600 mL of D5W.
Standard Dilution Protocol
The FDA-approved preparation method follows a two-step process 1:
- Initial reconstitution: Add 10 mL sterile water (without bacteriostatic agent) to each 50 mg vial to create a 5 mg/mL concentrate
- Final dilution: Further dilute 1:50 with 5% dextrose to achieve 0.1 mg/mL final concentration
For 160 mg amphotericin B deoxycholate:
- Final volume needed: 1600 mL of D5W
- Final concentration: 0.1 mg/mL
- Infusion time: 6-8 hours at 0.08 mg/kg/hour 2
Critical Preparation Requirements
The pH of D5W must exceed 4.2 before adding amphotericin B 1. Commercial D5W typically has pH ~3.7, which is below this threshold 3. If pH is below 4.2, add 1-2 mL of phosphate buffer (dibasic sodium phosphate 1.59 g + monobasic sodium phosphate 0.96 g per 100 mL water) 1.
Volume-Dependent Stability Concerns
Research demonstrates that concentration matters significantly for stability and deliverability 3:
- 25 mg/500 mL (0.05 mg/mL): Produces excessive particles >10 μm, causes filter blockage, only 11.3% of drug delivered
- 25 mg/250 mL (0.1 mg/mL): Meets pharmacopeial standards, flows completely
- 50 mg/500 mL (0.1 mg/mL): Meets pharmacopeial standards, flows completely
This explains why the standard 0.1 mg/mL concentration is critical - lower concentrations risk precipitation and incomplete drug delivery.
Alternative Concentrated Preparations
For central venous line administration, higher concentrations are stable 4:
- 0.92-1.40 mg/mL in D5W remains stable for 36 hours at both 6°C and 25°C
- These concentrated solutions are used when fluid restriction is necessary
However, guidelines consistently recommend the standard 0.1 mg/mL dilution for peripheral administration 2, 1.
Storage and Stability
- Standard dilution (0.1-0.25 mg/mL): Stable for 35 days at 4°C 5
- No light protection required during storage or infusion 6
- No bacteriostatic agent present: Use strict aseptic technique 1
Clinical Context
The 2023 Taiwan guidelines specify that amphotericin B deoxycholate (1-1.5 mg/kg/day) should be "administered in 5% dextrose with slow infusion over 6-8 h, at the rate of 0.08 mg/kg/hour" 2. This infusion rate and duration are designed to minimize infusion-related reactions while maintaining therapeutic efficacy.
Pre-medication with diphenhydramine or acetaminophen is recommended to prevent infusion reactions, and 1 L normal saline before and after infusion helps prevent nephrotoxicity 2.