LL-37 is an endogenous human cathelicidin peptide. Controlled clinical studies have examined topical LL-37 in hard-to-heal venous leg ulcers; a multicentre phase IIb trial did not find a significant difference in the full study population, with a post-hoc subgroup observation requiring further study.

Potential. Review the research and limitations before relying on this record.

LL-37 is the only human cathelicidin-derived antimicrobial peptide. It has broad-spectrum direct antimicrobial activity and separate immunomodulatory and chemotactic roles, and disrupts biofilms by inhibiting bacterial adhesion, downregulating biofilm-associated genes, suppressing quorum sensing and degrading biofilm matrix.

No pharmacokinetic or stability data for administered LL-37 is curated. Endogenous LL-37 is produced locally at epithelial surfaces, which is not the same exposure as an injected or topical dose of synthetic peptide.

No published, curated interaction record is available for this compound in the current library.

Most of the literature is in-vitro antimicrobial work, but LL-37 has been tested properly once: a multicentre prospective randomised placebo-controlled trial of topical LL-37 in hard-to-heal venous leg ulcers did not show a significant difference across the full study population, with a post-hoc subgroup observation that would need its own trial to mean anything. A 2023 review states plainly that many questions about in-vivo efficacy and safety remain unanswered.

LL-37 is described in the same reviews as acting as both an anti-inflammatory and a pro-inflammatory factor, and elevated cathelicidin activity is implicated in the pathogenesis of rosacea. That dual role is the central safety concern: more is not straightforwardly better. Cathelicidin LL-37 was added to FDA's Category 2 interim compounding list in September 2023.

This clinical research is topical and wound-specific. It does not establish effectiveness or safety for other routes, preparations, conditions, or self-directed use. No protocol or dosing guidance is provided.