Micafungin

Chemical Identity

Property	Value
Chemical Formula	C56H71N9O23S
Molecular Weight	1270.28 Da
CAS Number	235114-32-6
Peptide Class	Lipopeptide (Echinocandin)
Origin	Semi-synthetic (from Coleophoma empetri)

Structure

Micafungin is a semi-synthetic lipopeptide derived from the natural product FR901379 produced by Coleophoma empetri. It contains a cyclic hexapeptide core with a sulfated tyrosine and an N-linked lipophilic side chain. The sulfate group enhances water solubility compared to other echinocandins.

Mechanism of Action

Like other echinocandins, micafungin inhibits beta-1,3-D-glucan synthase, disrupting fungal cell wall biosynthesis. It is fungicidal against Candida species and has concentration-dependent activity against Aspergillus. The enzyme target is absent in mammals, providing excellent selectivity.

Clinical Applications

• Candidemia: First-line treatment option
• Esophageal candidiasis: Effective against fluconazole-resistant species
• Candidiasis prophylaxis: In hematopoietic stem cell transplant recipients
• Invasive aspergillosis: Salvage therapy

Pharmacokinetics

• Half-life: 11-17 hours
• Protein binding: >99%
• Metabolism: CYP3A4 (minor), catechol-O-methyltransferase
• Elimination: Hepatic (71% fecal)
• Dosing: 100 mg/day for candidemia, 50 mg/day for prophylaxis

Safety and Side Effects

Hepatotoxicity (elevated LFTs), hypokalemia, diarrhea, nausea, headache, and histamine-related reactions with rapid infusion. Well-tolerated in pediatric and neonatal populations.

References

• Pappas, P.G., et al. (2007). Micafungin versus caspofungin for candidemia. Clinical Infectious Diseases, 44, e56-e63.
• Chandrasekar, P.H., & Sobel, J.D. (2006). Micafungin: a new echinocandin. Clinical Infectious Diseases, 42, 1171-1178.