| Indication |
For use in the treatment of candidemia, acute disseminated candidiasis, and certain other invasive Candida infections, as well as esophageal candidiasis, and prophylaxis of Candida infections in patients undergoing hematopoietic stem cell transplantation. Micafungin is also used as an alternative for the treatment of oropharyngeal candidiases and has been used with some success as primary or salvage therapy, alone or in combination with other antifungals, for the treatment of invasive aspergillosis. |
| Mechanism of action |
Micafungin inhibits the synthesis of beta-1,3-D-glucan, an essential component of fungal cell walls which is not present in mammalian cells. It does this by inhibiting beta-1,3-D-glucan synthase. |
| Absorption |
Not absorbed orally |
| Protein binding |
Highly (>99%) protein bound in vitro, independent of plasma concentrations over the range of 10 to 100 µg/mL. The primary binding protein is albumin; however, micafungin, at therapeutically relevant concentrations, does not competitively displace bilirubin binding to albumin. Micafungin also binds to a lesser extent to a1-acid-glycoprotein. |
| Biotransformation |
Micafungin is metabolized to M-1 (catechol form) by arylsulfatase, with further metabolism to M-2 (methoxy form) by catechol-O-methyltransferase. M-5 is formed by hydroxylation at the side chain (w-1 position) of micafungin catalyzed by cytochrome P450 (CYP) isozymes. Even though micafungin is a substrate for and a weak inhibitor of CYP3A in vitro, hydroxylation by CYP3A is not a major pathway for micafungin metabolism in vivo. |
| Route of elimination |
Fecal excretion is the major route of elimination (total radioactivity at 28 days was 71% of the administered dose). |
| Toxicity |
Intravenous LD50 in rats is 125mg/kg. In dogs it is >200mg/kg. No cases of overdosage have been reported. Repeated daily doses up to 8 mg/kg (maximum total dose of 896 mg) in adult patients have been administered in clinical trials with no reported dose-limiting toxicity. The minimum lethal dose is 125 mg/kg in rats, equivalent to 8.1 times the recommended human clinical dose for esophageal candidiasis based on body surface area comparisons. |
| Affected organisms |
- Aspergillis, Candida and other fungi
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