Pexiganan

Antimicrobial Peptide / Topical

Also known as: MSI-78, Locilex

Synthetic Antimicrobial PeptidesResearch phase: Phase 3 (failed)Regulatory: Not approved. FDA declined approval after Phase 3 trials.

Mechanism

Pexiganan is a synthetic antimicrobial peptide derived from frog magainin-2. It was developed as a topical antibiotic cream for infected diabetic foot ulcers but did not gain FDA approval.

Technical detail

Pexiganan (MSI-78) is a 22-amino acid synthetic analog of magainin-2 with enhanced antimicrobial potency. It forms amphipathic alpha-helices that disrupt bacterial membranes via toroidal pore formation. Two Phase 3 trials for topical treatment of diabetic foot infections failed to demonstrate superiority over ofloxacin, and an FDA advisory committee did not recommend approval.

Evidence

Topical versus systemic antimicrobial therapy for treating mildly infected diabetic foot ulcers: a randomized, controlled, double-blinded, multicenter trial of pexiganan cream
Lipsky BA et al. (2008) — Clinical Infectious Diseases — PMID: 18990064
In two double-blind multicenter trials totaling 835 patients with mildly infected diabetic foot ulcers, topical pexiganan achieved clinical improvement, microbiologic eradication, and wound-healing rates equivalent to oral ofloxacin, with no significant emergence of pexiganan resistance reported.
moderate

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