How Much Does LL-37 Cost in 2026?

LL-37 (cathelicidin) is a 37-amino-acid antimicrobial peptide that is part of the human innate immune system. It has attracted growing research interest for its roles in infection defense, wound healing, and immune modulation. In April 2026, the FDA removed LL-37 from the Category 2 503A bulk drug substances list — a change that has affected compounding pharmacy supply and shifted research procurement to specialist suppliers.

Current LL-37 Prices by Supplier

LL-37 is a larger peptide (37 amino acids), which makes synthesis more complex and expensive compared to smaller research peptides. Pricing below reflects the most current available data; we are actively verifying post-reclassification pricing with all tracked suppliers.

5mg Vials

Prices sourced from publicly available supplier listings, May 2026. Verify current pricing directly with each supplier before ordering.

What Is LL-37?

LL-37 is the only known member of the cathelicidin family of antimicrobial peptides in humans. The name refers to its structure: it begins with two leucine (L) residues and contains 37 amino acids total. It is produced naturally by neutrophils, epithelial cells (skin, lungs, gut), and macrophages — particularly in response to infection and inflammation.

Unlike many research peptides that target a single receptor, LL-37 operates through multiple mechanisms. It directly disrupts bacterial cell membranes, modulates inflammatory cytokine responses, promotes wound healing and re-epithelialization, and plays a role in attracting immune cells to sites of infection. This multi-modal activity has made it one of the more extensively studied innate immune peptides.

What Researchers Study LL-37 For

• Antimicrobial activity — LL-37 has been studied against a broad range of bacteria, including antibiotic-resistant strains. It disrupts bacterial membranes through charge-based interactions, making resistance development slower than with conventional antibiotics.
• Wound healing and skin repair — Multiple studies have examined LL-37's role in accelerating re-epithelialization and wound closure, with particular interest in chronic wound models.
• Immune modulation — Research has looked at how LL-37 modulates Toll-like receptor signaling and the balance between pro- and anti-inflammatory cytokines.
• Respiratory and lung defense — LL-37 is present in lung fluid and airways; research has examined its role in respiratory infections and cystic fibrosis models.
• Inflammatory bowel disease — Animal and cell-culture studies have examined LL-37 in the context of intestinal epithelial repair and gut immune homeostasis.
• Cancer research — Some studies have explored both pro- and anti-tumor effects depending on cancer type and concentration, making this a complex and active research area.

LL-37 and the April 2026 FDA Reclassification

Until April 23, 2026, LL-37 was listed on the FDA's Category 2 503A bulk drug substances list, which allowed compounding pharmacies to prepare it for individual patients under a physician's order. On that date, the FDA removed LL-37 and 11 other peptides from Category 2 following a review that determined insufficient clinical evidence to justify continued listing.

This change primarily affects compounding pharmacy access — patients who were receiving LL-37 through a 503A compounding pharmacy can no longer do so legally. Research suppliers operating under different regulatory frameworks (selling to laboratories for non-clinical research) are not directly affected by the Category 2 removal.

The Pharmacy Compounding Advisory Committee (PCAC) is scheduled to meet July 23–24, 2026 to review these peptides further. There is a possibility that some peptides could be placed on the Category 1 list (active compounding encouraged) or considered for a Category 3 pathway if additional evidence is submitted.

See the full FDA Peptide Reclassification 2026 guide for detailed coverage of all 12 affected peptides.

Notable Research Suppliers (2026)

What to Look for in an LL-37 Supplier

Because LL-37 is a larger, more complex peptide than smaller research compounds, synthesis quality and purity verification are especially critical:

• Third-party COAs with HPLC purity data — 98%+ purity is the minimum standard; given LL-37's synthesis complexity, COA verification is non-negotiable.
• Named independent testing lab — The COA should specify which laboratory performed the analysis. In-house testing only is a red flag for larger peptides.
• Mass spectrometry confirmation — The best suppliers also provide MS data confirming the correct molecular weight, not just HPLC purity.
• Lyophilized powder form — LL-37 should be supplied as freeze-dried powder, not pre-dissolved in solution.
• Post-reclassification regulatory awareness — Legitimate research suppliers should be transparent about the April 2026 changes and how their operations are affected.

Frequently Asked Questions