How should each amphotericin B formulation be reconstituted according to manufacturer specifications?

Amphotericin B Reconstitution by Formulation

Each amphotericin B formulation requires specific reconstitution according to manufacturer specifications, with amphotericin B deoxycholate requiring reconstitution with 10 mL Sterile Water for Injection to achieve 5 mg/mL concentration, while lipid formulations have distinct preparation requirements.

Amphotericin B Deoxycholate (Fungizone)

Reconstitution Process

• Add 10 mL of Sterile Water for Injection USP to the 50 mg vial 1
• This creates a concentration of 5 mg amphotericin B per mL 1
• The lyophilized cake will dissolve to form a colloidal dispersion 1

Critical Reconstitution Technique

• Do NOT shake vigorously - this significantly increases particulate contamination from the amphotericin B-deoxycholate complex and silicone from vial components 2
• Gently swirl or rotate the vial instead
• The reconstituted solution should be filtered with membrane filters before dilution 2

Storage After Reconstitution

• The concentrate (5 mg/mL) may be stored:
  • 24 hours at room temperature (protected from light) 1
  • One week refrigerated at 2-8°C (protected from light) 1
• Discard any unused material after these timeframes 1

Dilution for Infusion

• Further dilute in 5% dextrose injection only 1, 3
• Final concentration should be 0.1 mg/mL or less for IV infusion 1
• The pH of the 5% dextrose must exceed 4.2 to prevent precipitation 3
• Do NOT use evacuated IV containers with buffers - these cause precipitation 3
• Use polyolefin, glass, or polyvinyl chloride IV containers 3
• Use in-line filters during administration 2

Infusion Preparation Stability

• Solutions prepared for IV infusion should be used promptly after preparation 1
• Protect from light during administration 1
• Maximum stability: 35 days for 0.25 mg/mL solutions, 36 hours for 1.4 mg/mL solutions when refrigerated 3

Lipid Formulations

General Principles

The three lipid formulations have different pharmacological properties and are NOT interchangeable 4:

1. Amphotericin B Lipid Complex (ABLC, Abelcet)

   • Administered at 5 mg/kg once daily 5
   • Infuse over 2 hours 5

2. Liposomal Amphotericin B (L-AmB, AmBisome)

   • Administered at 3-5 mg/kg once daily 5
   • Infuse over 1-2 hours 5
   • For CNS involvement: 10 mg/kg/day 6

3. Amphotericin B Colloidal Dispersion (ABCD, Amphotec/Amphocil)

   • Less commonly used
   • Specific reconstitution per manufacturer guidelines

Critical Safety Considerations

Infusion-Related Reactions

• Premedicate with diphenhydramine to reduce infusion reactions 5, 6
• For amphotericin B deoxycholate: consider acetaminophen as well 5
• Lipid formulation reactions occur within first 5 minutes and resolve with temporary interruption 5

Nephrotoxicity Prevention

• Saline loading: Give 1 L normal saline before and after amphotericin B deoxycholate infusion 6
• Infuse amphotericin B deoxycholate slowly over 6-8 hours at 0.08 mg/kg/hour 6
• Avoid concurrent nephrotoxic agents 7

Common Pitfalls to Avoid

• Never use bacteriostatic water - the formulation lacks preservatives 1
• Never shake vigorously during reconstitution 2
• Never mix with saline or electrolyte solutions - use only 5% dextrose for deoxycholate 1, 3
• Never interchange lipid formulations without dose adjustment 4
• Never expose to fluorescent light unnecessarily, though protection is less critical than previously thought 3