What is the recommended dosage and treatment protocol for Amphotericin (antifungal medication) B for severe fungal infections?

Amphotericin B Dosing for Severe Fungal Infections

For severe, life-threatening fungal infections, initiate treatment with liposomal amphotericin B at 3-5 mg/kg/day IV or amphotericin B deoxycholate at 0.7-1.0 mg/kg/day IV for 1-2 weeks until clinical improvement, then transition to oral azole therapy for completion of treatment. 1, 2

Formulation Selection

Lipid formulations are strongly preferred over amphotericin B deoxycholate due to significantly reduced nephrotoxicity and fewer infusion-related reactions, while maintaining equivalent efficacy 2, 3:

• Liposomal amphotericin B (AmBisome): 3-5 mg/kg/day IV is the preferred lipid formulation 1, 2, 4
• Amphotericin B lipid complex (ABLC): 3-5 mg/kg/day IV is an acceptable alternative 1, 2
• Amphotericin B deoxycholate: 0.7-1.0 mg/kg/day IV only if lipid formulations unavailable 1, 2, 5

Disease-Specific Dosing Protocols

CNS Infections (Meningitis, CNS Aspergillosis)

• Liposomal amphotericin B 5 mg/kg/day IV for 4-6 weeks, followed by oral azole therapy for at least 12 months until CSF abnormalities resolve 1, 2
• Higher doses required due to poor CNS penetration 1

Severe Pulmonary or Disseminated Disease

• Liposomal amphotericin B 3-5 mg/kg/day IV or amphotericin B deoxycholate 0.7-1.0 mg/kg/day for 1-2 weeks 1, 2
• Transition to itraconazole 200 mg PO three times daily for 3 days, then 200 mg twice daily to complete 6-12 months total therapy 1, 6

Mucormycosis (COVID-Associated or Otherwise)

• Liposomal amphotericin B 5 mg/kg/day IV for non-CNS disease 4
• 10 mg/kg/day IV for CNS involvement 4
• Continue for 4-6 weeks (induction/consolidation), then transition to posaconazole or isavuconazole for 3-6 months maintenance 4
• Immediate surgical debridement is mandatory and should not be delayed 4

Candidemia and Invasive Candidiasis

• Liposomal amphotericin B 3-5 mg/kg/day IV is an alternative to echinocandins 7, 4
• For critically ill patients or azole-resistant species, echinocandins are preferred first-line 4
• Amphotericin B deoxycholate 0.6-1.0 mg/kg/day is equivalent to fluconazole 400 mg/day but less well tolerated 7

Administration Guidelines

Amphotericin B Deoxycholate (if lipid formulations unavailable)

• Never exceed 1.5 mg/kg total daily dose - overdose can cause fatal cardiac arrest 5
• Reconstitute to 5 mg/mL, then dilute to 0.1 mg/mL in 5% dextrose (pH >4.2) 5
• Infuse over 2-6 hours depending on dose 5
• Premedicate with diphenhydramine or acetaminophen to reduce infusion reactions 4
• Administer 1L normal saline before and after infusion to minimize nephrotoxicity 4

Test Dose Protocol (for deoxycholate formulation)

• Give 1 mg in 20 mL 5% dextrose over 20-30 minutes 5
• Monitor temperature, pulse, respiration, blood pressure every 30 minutes for 2-4 hours 5
• If well tolerated, initiate 0.25-0.3 mg/kg/day; if poorly tolerated, start with 5-10 mg/day and escalate gradually 5

Lipid Formulations

• No test dose required 3
• Infuse over 2-3 hours 4
• Better tolerated with significantly less nephrotoxicity than deoxycholate 8, 3

Duration by Infection Type

• Blastomycosis (pulmonary/disseminated): 6-12 months total 1, 6
• Osteoarticular infections: Minimum 12 months 1, 2, 6
• CNS infections: Minimum 12 months and until CSF normalization 1, 6
• Sporotrichosis (pulmonary/disseminated): Minimum 12 months 2
• Mucormycosis: 4-6 weeks IV, then 3-6 months oral maintenance 4

Critical Monitoring Parameters

• Serum creatinine and BUN at baseline and at least twice weekly during therapy 5, 9
• Serum potassium and magnesium - hypokalemia occurs in 6.2% of patients 9
• Liver function tests - hepatotoxicity in 5.2% 9
• Complete blood count for bone marrow suppression 5

Common Pitfalls and Caveats

Nephrotoxicity is dose-dependent and cumulative - lipid formulations reduce but do not eliminate this risk 8, 3:

• Mean creatinine increases from 0.9 to 1.1 mg/dL during treatment even with liposomal formulation 9
• Nephrotoxicity occurs in 4.2% with liposomal amphotericin B versus significantly higher rates with deoxycholate 9

Infusion reactions are common with deoxycholate (fever, chills, rigors) but markedly reduced with lipid formulations 3:

• Premedication reduces but does not eliminate reactions 4
• Reactions typically decrease with subsequent infusions 8

Drug interactions are minimal compared to azoles - amphotericin B does not inhibit cytochrome P450 6

Higher doses (10 mg/kg/day) do not improve efficacy but increase nephrotoxicity - avoid exceeding recommended doses 3

Verify product name and dose pre-administration - fatal errors have occurred with overdosing 5