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    LL-37 Peptide: A Provider's Guide to Identity, Vial Format, and Access

    Short answer: The LL-37 peptide is a 37-amino-acid peptide cleaved from the human cathelicidin precursor protein hCAP18, encoded by the CAMP gene. UniProt classifies the precursor in the cathelicidin family and names the mature peptide "Antibacterial peptide LL-37" (UniProt P49913). Gudmundsson and colleagues isolated and structurally confirmed mature LL-37 from human granulocytes in 1996 (Gudmundsson et al., 1996). PubChem lists it as CID 16198951, molecular formula C205H340N60O53, molecular weight ≈4493 g/mol (PubChem). For clinics, Biomed Peptides supplies LL-37 5 mg as a lyophilized powder in a sealed vial, to verified licensed providers only.

    This guide covers what the compound is, where it appears on FDA's compounding pages, how it's supplied and stored, and how provider access works. Clinical decisions stay with the prescribing clinician.

    What is the LL-37 peptide?

    Origin and name

    The name is literal. LL-37 is 37 residues long and starts with two leucines (L-L). It's the C-terminal portion of hCAP18, the human cathelicidin precursor protein. In their 1996 paper, Gudmundsson and colleagues characterized the complete human gene (then called FALL39), concluded it is "the only member of the cathelin gene family present in the human genome," and determined the mature peptide isolated from granulocytes to be LL-37 (Gudmundsson et al., 1996).

    Why it's called an "LL-37 antimicrobial peptide"

    You'll often see the phrase LL-37 antimicrobial peptide. That's a scientific classification, not a clinical description. UniProt places the human precursor in the cathelicidin family, gives it the recommended name "Cathelicidin antimicrobial peptide," and names the mature fragment "Antibacterial peptide LL-37" (UniProt P49913). PubChem lists "cathelicidin LL-37," "antimicrobial peptide LL-37," "hCAP18," and the INN ropocamptide as synonyms (PubChem). FDA's compounding pages use "Cathelicidin LL-37" (FDA).

    Sequence and structure

    UniProt maps LL-37 to residues 134–170 of the 170-residue human precursor (UniProt P49913). The one-letter sequence is:

    LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES

    Attribute Value
    Common names LL-37, cathelicidin LL-37, hCAP18-derived peptide
    Nonproprietary name (PubChem) Ropocamptide
    Length 37 amino acids
    Molecular formula C205H340N60O53
    Molecular weight ≈4493 g/mol
    CAS (as listed in PubChem) 154947-66-7
    PubChem CID 16198951
    UniProt (human precursor) P49913
    Family (UniProt) Cathelicidin family

    The same precursor gives rise to several related fragments that UniProt lists separately, including FALL-39, LL-29, LL-23, and KR-20 (UniProt P49913). That's a practical reason to check the certificate of analysis (COA) closely. The mass spectrometry result should match the ≈4493 Da expected mass, and the sequence should match all 37 residues above, not a shorter or longer fragment.

    Regulatory context: FDA's 503A pages

    Section 503A sets the rules for which bulk drug substances pharmacists and physicians may compound with. A substance generally has to have a USP or NF monograph, be a component of an FDA-approved drug, or appear on FDA's 503A bulks list. FDA also requires a valid COA and an FDA-registered (section 510) manufacturing establishment (FDA).

    Here's what FDA's own pages currently show for LL-37:

    • FDA's page on bulk drug substances that may present significant safety risks lists Cathelicidin LL-37 under "Bulk drug substances nominated but withdrawn," which FDA describes as substances "previously in category 2 of the interim policies" whose nominations "were withdrawn by the nominators." The page summarizes the concerns FDA identified, and providers should read it directly. The content is marked current as of April 22, 2026 (FDA).
    • FDA's list of substances nominated under 503A (updated May 14, 2026) doesn't name LL-37 or cathelicidin in category 1, 2, or 3 (FDA nominations list).

    These pages change often. Confirm current status with your compounding pharmacy before you make any formulary decision. For background, see what a 503A pharmacy is.

    How LL-37 is supplied to clinics

    Lyophilized 5 mg vial

    LL-37 ships as a lyophilized (freeze-dried) powder in a sealed vial. Manufacturer guidance says peptides shouldn't be stored in solution because they "may slowly undergo chemical degradation," and recommends keeping them as a lyophilizate in a tightly closed container for longer storage (Bachem). The Biomed Peptides lyophilized catalog lists LL-37 5 mg. Make sure the vial label, the COA, and your records all show the same strength. Our lyophilized peptides guide explains the format.

    Storage on receipt

    • Keep vials sealed, dry, and protected from light. Follow the product label first.
    • For long-term holding, Bachem recommends storing peptide lyophilizates below −15 °C, with lower temperatures preferred. Refrigeration at 4 °C is acceptable for short-term use (Bachem).
    • Peptides tend to be hygroscopic. Let a cold vial reach room temperature before you open it, so moisture doesn't condense on the powder (Bachem).
    • Bachem notes that peptides containing Asn, Gln, Met, Cys, and/or Trp have limited shelf lives. LL-37 contains glutamine (Q) and asparagine (N), which is one more reason to follow the labeled expiration and storage conditions.

    Our lyophilized peptides storage guide covers each step in detail. For the diluent, see bacteriostatic water for peptides.

    Documentation to request

    Ask for these with every LL-37 lot:

    • Lot-specific COA with an identity result (typically mass spectrometry matching ≈4493 Da), HPLC purity, and peptide content where reported
    • Endotoxin results where applicable
    • Manufacturer and site information, since 503A requires a section 510-registered establishment for bulk drug substances (FDA)
    • Labeled storage conditions and expiration

    Our peptide COA and third-party testing guide explains how to read each section of a COA and match it to the vial in hand.

    LL-37 peptide buy: how provider access works

    Many results for "ll 37 peptide buy" are consumer storefronts. Biomed Peptides works differently. We supply physician-use product only to licensed healthcare providers, and we don't sell to patients or consumers.

    1. Submit the provider application.
    2. Our team verifies your credentials, usually within 24–48 hours.
    3. Approved accounts can view pricing, the full lyophilized catalog, and lot documentation.
    4. Order for office use or patient-specific fulfillment, with shipping to all 50 states.

    Source LL-37 for your practice

    Licensed practices and med spas can apply for provider access to view LL-37 5 mg pricing and COAs, or browse the lyophilized catalog to plan their formulary.

    FAQ

    What is the LL-37 peptide?

    LL-37 is a 37-amino-acid peptide cleaved from hCAP18, the human cathelicidin precursor encoded by the CAMP gene. PubChem lists its molecular weight as about 4493 g/mol (CID 16198951).

    Why is LL-37 called an antimicrobial peptide?

    It's a scientific classification, not a clinical description. UniProt places LL-37's human precursor in the cathelicidin family and gives it the recommended name "Cathelicidin antimicrobial peptide."

    What is LL-37's status on FDA's 503A pages?

    FDA's significant-safety-risks page (current as of April 22, 2026) lists Cathelicidin LL-37 among substances previously in category 2 whose nominations were withdrawn. FDA's May 14, 2026 nominations list does not name it in categories 1–3. Confirm current status with your compounding pharmacy.

    What vial size does Biomed Peptides carry?

    The catalog lists LL-37 5 mg as a lyophilized powder in a sealed vial.

    Where can a practice buy LL-37?

    From a provider-only supplier that verifies licensure. Biomed Peptides supplies LL-37 to approved providers. Apply at /apply to see pricing and documentation.

    Sources

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