Recovery · Investigational
Cathelicidin LL-37 Fragments
No lawful US pathway
01 · Overview
Cathelicidin LL-37 fragments are truncated or modified sequences derived from the human antimicrobial peptide LL-37, which is a 37-amino acid cleavage product of the cathelicidin precursor hCAP18. Shorter fragments such as KR-12 and FK-12 have been designed to retain antimicrobial activity while reducing toxicity to human cells (PMID 29737589).
Engineered LL-37-derived peptides such as OP-145 (PMID 37508259) and P60.4Ac (PMID 27114278) have been developed as topical anti-infectives.
02 · Research summary & key findings
In vitro, LL-37 fragments including KS-30, KR-20, and KR-12 killed multidrug-resistant Acinetobacter baumannii and inhibited biofilms (PMID 24071034), and 12-residue fragments showed antibiofilm activity, lower cytotoxicity, and wound healing potential in a keratinocyte cell model (PMID 29737589). In a randomized, placebo-controlled phase IIa study of 34 adults with chronic suppurative otitis media, ear drops containing P60.4Ac achieved treatment success in 47 percent versus 6 percent with placebo and were well tolerated (PMID 32287316). No LL-37 fragment has been approved for therapeutic use.
03 · Regulatory status
Cathelicidin LL-37 Fragments is in the investigational stage. While preclinical and early-phase data exist, it has not received regulatory approval for clinical use in the United States.
No lawful pathway today
Cathelicidin LL-37 Fragments is not FDA-approved and does not currently have a lawful prescription or compounding pathway in the United States, so we do not sell it and will not book a consultation for it. That can change: in 2026 FDA began reviewing several peptides for compounding. If you are working on the goal it is studied for, a licensed clinician can tell you what is lawfully available, which may be something else.
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Cathelicidin LL-37 Fragments is an investigational compound, is not FDA-approved, and has no lawful US compounding pathway, so we do not offer it and no clinician we work with will prescribe it. Products sold online as “research chemicals” are not made or tested to the standards required of medicines. If you are working on injury recovery and tissue repair, a licensed clinician can tell you at a free consultation whether an FDA-approved or lawfully compounded treatment fits you, or whether nothing does.
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04 · Administration routes
- Topical
- Subcutaneous injection
References
- [1]The human antimicrobial peptide LL-37 and its fragments possess both antimicrobial and antibiofilm activities against multidrug-resistant Acinetobacter baumannii Peptides, 2013. PMID 24071034
- [2]Antimicrobial Peptide P60.4Ac-Containing Creams and Gel for Eradication of Methicillin-Resistant Staphylococcus aureus from Cultured Skin and Airway Epithelial Surfaces Antimicrob Agents Chemother, 2016. PMID 27114278
- [3]LL-37 fragments have antimicrobial activity against Staphylococcus epidermidis biofilms and wound healing potential in HaCaT cell line J Pept Sci, 2018. PMID 29737589
- [4]Ototopical drops containing a novel antibacterial synthetic peptide: Safety and efficacy in adults with chronic suppurative otitis media PLoS One, 2020. PMID 32287316
- [5]Bactericidal Activity to Escherichia coli: Different Modes of Action of Two 24-Mer Peptides SAAP-148 and OP-145, Both Derived from Human Cathelicidine LL-37 Antibiotics (Basel), 2023. PMID 37508259
Primary literature
- PubMed: "Cathelicidin LL-37 Fragments"
Peer-reviewed literature indexed by the National Library of Medicine.
- ClinicalTrials.gov: "Cathelicidin LL-37 Fragments"
Registered interventional and observational studies, including status and phase.
- PubChem: "Cathelicidin LL-37 Fragments"
Chemical structure, molecular properties, and bioactivity data.
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Disclaimer: This information is provided for educational and research purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any peptide therapy. The Peptide Association does not endorse or recommend any specific treatment protocol. See our editorial policy for how this content is produced and reviewed. Clinicians: join the network.