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Evidence: HighPeptideDiscontinuedAntimicrobial peptide (magainin analogue)Not approved · phase 3 topical trialsInfected diabetic foot ulcers

Pexiganan

A 22-amino-acid copy of a frog-skin defence peptide, tested as a cream for infected diabetic foot ulcers and never approved

Pexiganan is a synthetic 22-amino-acid cationic peptide modelled on magainin 2, a defence peptide from frog skin. In the laboratory it kills a broad range of bacteria, apparently by disrupting their membranes. As a 1% cream it was compared with oral ofloxacin in two phase 3 trials in 835 people with mildly infected diabetic foot ulcers: about 85% to 90% improved on either treatment, though one trial missed its equivalence target. It has never been approved.

At a Glance Read Research →
Overview

What is it?

Magainin 2 is one of the peptides frog skin uses to fend off microbes. Pexiganan, also called MSI-78, is a 22-amino-acid synthetic analogue, thought to act by disturbing the permeability of bacterial membranes. In laboratory testing, 99% of aerobic strains were susceptible at the breakpoint used and 89% to 97% of anaerobes, and repeated passage did not produce resistance in two strains of Staphylococcus aureus.

Its clinical test was topical treatment of mildly infected diabetic foot ulcers. In two double-blind trials of 835 patients, pexiganan cream was compared with oral ofloxacin. Study 303 failed to show equivalence; study 304 and the combined data did, with clinical improvement in 85% to 90% on both treatments and similar rates of worsening cellulitis and amputation. Resistance to ofloxacin emerged in some patients, while none of significance emerged to pexiganan. By one review's count, pathogens were eradicated at the end of therapy in 66% of pexiganan patients against 82% on ofloxacin.

Bacteria from those trials, and later surveillance isolates from diabetic foot infections, remained susceptible in the laboratory. Pexiganan has never been approved: FDA's Drugs@FDA database and EMA's register have no entry for it.

Structured data

At a Glance

Every value in this table is printed from the Grey Peptides dataset, the same record the compound explorer and comparison tool read, so the three can never disagree.

ClassA 22-amino-acid synthetic analog of magainin-2 (originally isolated from African clawed frog Xenopus laevis skin) developed as a topical antimicrobial peptide for diabetic foot ulcer infection; twice rejected by the FDA despite two rounds of Phase 3 trials spanning nearly two decades.
SequenceGly-Ile-Gly-Lys-Phe-Leu-Lys-Lys-Ala-Lys-Lys-Phe-Gly-Lys-Ala-Phe-Val-Lys-Ile-Leu-Lys-Lys (amidated C-terminus)
FormulaC122H210N32O22
Molecular weight2477.2 g/mol
Half-lifeTopical; minimal systemic absorption
Studied dose1% cream, applied twice daily (twice daily, topical)
US statusDiscontinued
Evidence levelHigh
Last reviewed2026-09-30

Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.

Evidence

Published Research

These are the studies behind pexiganan, read from their PubMed abstracts: the phase 3 trials, reviews, laboratory susceptibility studies and a rat wound model.

Human2008

Two phase 3 trials against oral ofloxacin

In 835 patients with mildly infected diabetic foot ulcers, study 303 failed to show equivalence, but study 304 and the combined data showed equivalent clinical improvement (85% to 90%), pathogen eradication (42% to 47%) and wound healing; worsening cellulitis and amputation did not differ, and no significant resistance to pexiganan emerged.

PMID: 18990064
Review1998

Pexiganan acetate

A 22-amino-acid analogue of magainin 2 with activity against aerobes and anaerobes. In the two phase 3 trials, clinical cure or improvement was about 90% with both treatments, while pathogens were eradicated in 82% on ofloxacin and 66% on pexiganan at the end of therapy.

PMID: 9878992
In Vitro1999

2,515 isolates from the trial patients

Bacteria grown from the ulcers of 835 trial patients were broadly susceptible: MIC90 values for the commonest Gram-positive aerobes, including Staphylococcus aureus, were 16 µg/mL or less.

PMID: 10529881
In Vitro2015

Surveillance isolates from diabetic foot infections

Against 2013 SENTRY isolates from diabetic foot infections, the MIC50 and MIC90 were 16 and 32 µg/mL; common Gram-negative pathogens had MICs of 8 to 16 µg/mL.

PMID: 25583717
Animal2005

Collagen films in infected rat wounds

Pexiganan incorporated into collagen films was released with sustained activity over 72 hours against Pseudomonas aeruginosa and Staphylococcus aureus in an infected rat wound model.

PMID: 15800884
Safety

Side Effects & Contraindications

Reported Side Effects

From the phase 3 trials and reviews.

● Worsening cellulitis (2% to 4%) and amputation (2% to 3%), no different from oral ofloxacin
● Limited data suggesting it is well tolerated as a cream

Contraindications & Cautions

Pexiganan has no approved label. These cautions follow from the evidence.

● Products sold outside a trial — identity and quality are unverified
● Serious or spreading infections — the trials enrolled only mild infections
● Tested athletes — see the Sport (WADA) row below
Questions

Frequently Asked Questions

?What is pexiganan?

A synthetic 22-amino-acid antimicrobial peptide modelled on magainin 2 from frog skin, tested as a 1% cream for infected diabetic foot ulcers.

?Did it work?

In two phase 3 trials, about 85% to 90% improved on either pexiganan cream or oral ofloxacin; one trial failed to show equivalence and ofloxacin eradicated pathogens more often.

?Is pexiganan approved?

No. FDA's Drugs@FDA database and EMA's register have no entry for it.

Bibliography

References

  1. [pubmed] Lipsky BA, et al. "Topical versus systemic antimicrobial therapy for treating mildly infected diabetic foot ulcers: a randomized, controlled, double-blinded, multicenter trial of pexiganan cream." Clin Infect Dis, 2008;47(12):1537-45. PMID: 18990064.
  2. [pubmed] Lamb HM, et al. "Pexiganan acetate." Drugs, 1998;56(6):1047-52; discussion 1053-4. PMID: 9878992.
  3. [pubmed] Ge Y, et al. "In vitro susceptibility to pexiganan of bacteria isolated from infected diabetic foot ulcers." Diagn Microbiol Infect Dis, 1999;35(1):45-53. PMID: 10529881.
  4. [pubmed] Flamm RK, et al. "In vitro spectrum of pexiganan activity when tested against pathogens from diabetic foot infections and with selected resistance mechanisms." Antimicrob Agents Chemother, 2015;59(3):1751-4. PMID: 25583717.
  5. [pubmed] Gopinath D, et al. "Pexiganan-incorporated collagen matrices for infected wound-healing processes in rat." J Biomed Mater Res A, 2005;73(3):320-31. PMID: 15800884.
  6. [fda] FDA. Drugs@FDA (openFDA): no application for pexiganan. Read September 30, 2026.
  7. [other] European Medicines Agency. Medicines register: no entry for pexiganan. Read September 30, 2026.

Sources & Citations

Every study on this page was read from its PubMed record. Regulatory status comes from FDA's Drugs@FDA database and EMA's register, read September 30, 2026. Grey Peptides sells nothing and links to no vendor.

Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Consult a licensed healthcare provider before making health decisions.

Last reviewed: 2026-09-30