What is the recommended dose of micofungin (antifungal medication) for adult and pediatric patients with normal and impaired renal (kidney function) and hepatic (liver function) function?

Micafungin Dosing Recommendations

Adult Dosing

For invasive candidiasis or candidemia, administer micafungin 100 mg IV once daily, continuing for at least 14 days after documented clearance of Candida from bloodstream and resolution of symptoms. 1, 2, 3

Treatment Indications

• Invasive candidiasis/candidemia: 100 mg IV once daily 1, 2, 3
• Esophageal candidiasis: 150 mg IV once daily for 14-21 days until clinical improvement 1, 2
• HSCT prophylaxis: 50 mg IV once daily, initiated after the last dose of chemotherapy and continued until neutrophil recovery 2

Species-Specific Considerations

• For Candida glabrata and Candida krusei infections, micafungin 100 mg daily achieves a clinical cure rate of 73.5% and is strongly preferred over azoles 2, 4
• For Candida parapsilosis, micafungin demonstrates higher MICs in vitro, but clinical trials have not shown reduced efficacy; however, fluconazole may be preferred if susceptibility is confirmed 1, 2

Pediatric Dosing

For children ≥4 months of age with invasive candidiasis, administer micafungin 2 mg/kg IV once daily (maximum 100 mg). 2

Age-Specific Recommendations

• Children ≥4 months: 2 mg/kg IV once daily (maximum 100 mg) for invasive candidiasis 2
• HSCT prophylaxis in pediatrics: 1 mg/kg IV once daily from last chemotherapy dose until neutrophil recovery 2
• Premature neonates: Higher doses of 4-10 mg/kg may be required due to increased clearance (40-80 mL/h/kg), though the clinical significance is debated given the eightfold higher free fraction of unbound drug 5

Renal Impairment

No dose adjustment is necessary for any degree of renal impairment, including dialysis, as micafungin undergoes nonenzymatic degradation rather than renal elimination. 1, 2

• Micafungin is not significantly eliminated by the kidneys, with clearance of 10.4 mL/h/kg independent of renal function 5
• Standard dosing can be maintained in patients with acute kidney injury or end-stage renal disease 1, 2

Hepatic Impairment

No dose adjustment is necessary for moderate or severe hepatic impairment, as micafungin undergoes minimal hepatic metabolism. 1, 2

• Unlike caspofungin (which requires dose reduction in moderate-to-severe hepatic dysfunction), micafungin does not require adjustment 1
• Micafungin is metabolized by arylsulfatase, catechol-O-methyltransferase, and several CYP isoenzymes (3A4, 1A2, 2B6, 2C), but these pathways do not necessitate dose modification even in severe hepatic dysfunction 5

Critical Considerations

Drug Interactions

• Micafungin is not significantly metabolized by the CYP450 3A system, resulting in minimal drug-drug interactions compared to azoles 6
• This makes micafungin particularly advantageous in patients receiving multiple concomitant medications, including immunosuppressants 6

Special Populations Requiring Attention

• Critically ill patients and burn patients: Exposure to micafungin is significantly lower compared to healthy volunteers, which may impact efficacy; however, current guidelines do not recommend routine dose escalation 5
• Hematology patients: Lower micafungin exposure has been documented, though standard dosing remains recommended 5

Common Pitfalls to Avoid

• Do not delay source control: Remove central venous catheters when feasible, as catheter retention is associated with treatment failure in candidemia 3, 4
• Do not use fluconazole empirically in severely ill patients: Echinocandins (including micafungin) are strongly preferred for critically ill or neutropenic patients 3
• Do not prematurely discontinue therapy: Continue treatment for the full 14 days after bloodstream clearance and symptom resolution to prevent relapse 2, 3
• Do not assume adequate peritoneal penetration: Echinocandins achieve limited concentrations in peritoneal fluid due to high protein binding (>95%), which may be relevant in intra-abdominal candidiasis 7