What it is
Micafungin is an antifungal whose core is a ring of six amino acids carrying a fatty tail. ChEBI, as shown on PubChem (CID 477468), calls it "a cyclic hexapeptide echinocandin antibiotic"; the US label calls it "a semisynthetic lipopeptide (echinocandin)". Both describe the same thing: a small peptide ring, closed on itself, with a long fat-loving side chain attached.
It is not a peptide in the everyday sense of a hormone or a supplement. Most of the ring's building blocks are modified amino acids — the label's chemical name includes a dihydroxy-ornithine and a substituted hydroxy-threonine — and the molecule is made by chemistry on a natural product, not by stringing standard amino acids together.
The label gives its source and formula: it is made by chemically modifying a fermentation product of the fungus Coleophoma empetri F-11899, and micafungin sodium is C56H70N9NaO23S, molecular weight 1,292.26.
How it works
The label's mechanism is one sentence long: micafungin inhibits the synthesis of 1,3-beta-D-glucan, "an essential component of fungal cell walls, which is not present in mammalian cells." That selectivity — a target the fungus has and human cells do not — is what the label's wording emphasises.
The label also records resistance: clinical failures linked to mutations in the FKS component of the glucan-synthase enzyme.
What the label's trials show
| Use (label) | Trial design | Result |
|---|---|---|
| Candidemia and invasive candidiasis | Randomised, double-blind, vs caspofungin (70 mg then 50 mg/day) | Success at end of IV therapy 135/191 (70.7%) on micafungin 100 mg/day vs 119/188 (63.3%); difference 7.4, 95% CI −2.0 to 16.3 |
| Oesophageal candidiasis | Two controlled trials, 763 patients, vs fluconazole | Endoscopic, clinical and mycological outcomes described as comparable |
| Prevention after stem-cell transplant | Randomised, double-blind, 882 patients, vs fluconazole 400 mg/day | Success 343/425 (80.7%) on micafungin 50 mg/day vs 337/457 (73.7%); +7.0, 95% CI 1.5 to 12.5. Proven breakthrough Candida infections: 4 vs 2 |
Two notes the label itself makes. In the candidemia trial the confidence interval crosses zero, so the trial supports similar performance rather than superiority. And in the transplant trial the label states that efficacy against fungi other than Candida has not been established.
Doses on the label
Reported from the label, for reference; the dose for any patient is set by the treating team.
| Indication | Adults (label) |
|---|---|
| Candidemia, disseminated candidiasis, peritonitis, abscesses | 100 mg once daily |
| Oesophageal candidiasis | 150 mg once daily |
| Prevention in stem-cell transplant recipients | 50 mg once daily |
Children's doses are weight-based, and infants under 4 months have a separate dose for one indication. Every dose is an intravenous infusion over one hour. Across the label's pharmacokinetic table, the half-life in adults runs from about 13 to 17 hours.
Safety
The label's warnings cover anaphylaxis, haemolysis (including acute intravascular haemolysis in a healthy volunteer), liver test abnormalities with isolated cases of hepatitis and liver failure, kidney effects and infusion reactions.
One finding comes from animals and is labelled as such: in rats given 32 mg/kg/day for 3 to 6 months — about 8 times the highest human dose by exposure — liver adenomas and carcinomas appeared after long recovery periods of up to 18–21 months (label, section 13.1). That is a rat result; the label does not report it in people.
Where it stands
- Approved in the US since 2005-03-16 (Mycamine, Astellas, NDA 021506, a new molecular entity).
- Brand: those Mycamine vials are listed as discontinued, with a Federal Register determination that this was not for safety or effectiveness reasons. A second 2005 Mycamine record (NDA 021754) still shows prescription status in the database.
- Generics: 11 generic applications and Baxter's ready-mixed infusion bag (NDA 216142, 2023-09-29) are listed as prescription products; three other applications are discontinued (Drugs@FDA, 2026-10-06).
- Research record: PubMed indexes 2,382 records, 44 tagged as randomised trials (2026-10-06).
Related reading
Micafungin's wall-building target is a sugar polymer; the bacterial equivalent, a sugar mesh cross-linked by short peptides, is explained in the peptidoglycan entry. The body's own antimicrobial peptide is described in the LL-37 entry, and other approved peptide drugs in the library include linaclotide and ziconotide.