Quickstart Highlights
LL-37 (also known as CAP-18) is a 37-amino-acid cationic antimicrobial peptide derived from the C-terminal of human cathelicidin (hCAP18). It is the only known human cathelicidin, exhibiting broad-spectrum antibacterial activity and immune-modulating properties. This educational protocol presents a once-daily subcutaneous approach with nominal volume calculations that require verification against the actual device.
- Reconstitute: Add 3.0 mL BAC water per labelled 10 mg vial; calculations assume a final volume of 3.0 mL and nominal concentration of 3.33 mg/mL.
- Typical daily range: 50–200 mcg once daily (gradual titration) for a 2–4 week cycle.
- Scale conversion: At 3.33 mg/mL, 1 U-100 unit = 0.01 mL ≈ 33.3 mcg; 100 mcg = 3 units, 200 mcg = 6 units. Confirm actual device markings; this arithmetic does not establish measurement accuracy.
- Storage: Lyophilized: freeze at −20 °C (−4 °F); after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) for up to 4 weeks; avoid freeze–thaw cycles.
Dosing & Reconstitution Guide
Standard / Gradual Approach (3 mL = 3.33 mg/mL)
| Week | Daily Dose (mcg) | Calculated volume | U-100 scale value (1 mL capacity) | V1 nominal setting (units) |
|---|---|---|---|---|
| Week 1 | 50 mcg | 0.015 mL | 1.5 units (requires matching fractional-unit markings) | Not representable in whole units |
| Week 2 | 100 mcg | 0.03 mL | 3 units | 3 units |
| Weeks 3–4 | 150–200 mcg | 0.045–0.06 mL | 4.5–6 units | Endpoints: Not representable in whole units / 6 units; intermediate amounts require a separate check |
Calculation basis: The table uses the labelled 10 mg amount and assumes a final solution volume of 3.0 mL (3.33 mg/mL). BAC volume does not change the amount of peptide. These are nominal calculations, not validation of preparation, compatibility or treatment.
Frequency: Inject once daily subcutaneously (or 5 days on / 2 days off) for 2–4 weeks, then take at least 2 weeks off. 200 mcg is the ceiling; higher doses and long courses are where injection-site reactions and pro-inflammatory signalling are reported. For ≤10-unit (≤0.10 mL) administrations, consider 30- or 50-unit insulin syringes for improved readability.
Reconstitution Steps
- Draw 3.0 mL bacteriostatic water with a sterile syringe.
- Inject slowly down the vial wall; avoid foaming.
- Gently swirl/roll until dissolved (do not shake).
- Label and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.
Supplies Needed
Plan based on a 2–4 week daily cycle (about 4.5 mg used over 4 weeks).
- Peptide Vials (LL-37, 10 mg each):
- 2 weeks: 1 vial
- 4 weeks: 1 vial
- Insulin Syringes (U-100):
- Per week: 7 syringes (1/day)
- 2 weeks: 14 syringes
- 4 weeks: 28 syringes
- Bacteriostatic Water (30 mL bottles): Use 3.0 mL per vial → 1 × 30 mL bottle.
- Alcohol Swabs: One for the vial stopper + one for the injection site each injection.
- Per week: 14 swabs
- 2 weeks: 28 swabs
- 4 weeks: 56 swabs → 1 × 100-count box
Protocol Overview
Concise summary of the once-daily regimen.
- Goal: Support antimicrobial defense and wound-healing processes.
- Schedule: Daily subcutaneous injections (or 5 days on / 2 off) for 2–4 weeks, followed by at least 2 weeks off.
- Dose Range: 50–200 mcg daily with gradual titration.
- Reconstitution: 3.0 mL BAC per labelled 10 mg vial; nominal 3.33 mg/mL under the stated final-volume assumption.
- Storage: Lyophilized frozen; reconstituted refrigerated; avoid repeated freeze–thaw.
Dosing Protocol
Suggested daily titration approach.
- Start: 50 mcg daily for Week 1; 100 mcg daily for Week 2.
- Target: 150–200 mcg daily by Weeks 3–4; 200 mcg is the ceiling.
- Frequency: Once per day (subcutaneous); optional 5-on/2-off schedule.
- Cycle Length: 2–4 weeks on, then at least 2 weeks off. No extension.
- Timing: Any consistent time; rotate injection sites.
Storage Instructions
Proper storage preserves peptide quality.
- Lyophilized: Store at −20 °C (−4 °F) in dry, dark conditions; stable ~24 months.
- Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F) for up to 4 weeks; frozen at −20 °C (−4 °F) for up to 6 months.
- Allow vials to reach room temperature before opening to reduce condensation uptake.
Important Notes
Practical considerations for consistency and safety.
- Use new sterile insulin syringes; dispose in a sharps container.
- Rotate injection sites (abdomen, thighs, upper arms) to reduce local irritation.
- Inject slowly; wait a few seconds before withdrawing the needle.
- Document daily dose and site rotation to maintain consistency.
- Early-phase doses (≤10 units) benefit from 30- or 50-unit syringes for precision.
How This Works
LL-37 exerts both direct and indirect antimicrobial effects. Its amphipathic, cationic α-helical structure (net +6 charge) allows it to preferentially bind and disrupt negatively charged microbial membranes. Beyond direct killing, LL-37 modulates host immunity: in murine sepsis models, it induced neutrophils to release microvesicles rich in antimicrobial proteins, lowering bacterial burden and improving survival. LL-37 can also bind bacterial lipopolysaccharide (LPS) and block its interaction with CD14/TLR4, reducing endotoxin-triggered TNF release and neutrophil apoptosis. These combined mechanisms help explain its potential in infection control and tissue-repair contexts.
Potential Benefits & Side Effects
Observations from preclinical and clinical literature.
- In chronic venous leg ulcers (which often lack endogenous LL-37), topical treatment with synthetic LL-37 significantly accelerated healing rates compared to placebo.
- In diabetic foot ulcer trials, LL-37 cream improved granulation tissue formation and wound closure.
- Broad-spectrum antimicrobial action helps clear infections; in experimental sepsis models, LL-37 treatment reduced bacterial loads and mortality.
- Generally well tolerated; occasional mild injection-site reactions (redness, itch) may occur with subcutaneous administration.
Lifestyle Factors
Complementary strategies for best outcomes.
- Optimize vitamin D status, as vitamin D upregulates endogenous cathelicidin/LL-37 expression.
- Support wound healing with adequate protein intake and micronutrient sufficiency (zinc, vitamin C).
- Maintain proper wound hygiene and dressing protocols if using for tissue-repair goals.
- Prioritize sleep and stress management to support immune function and recovery.
Injection Technique
General subcutaneous guidance from clinical best-practice resources.
- Clean the vial stopper and skin with alcohol; allow to dry.
- Pinch a skinfold; insert the needle at 45–90° into subcutaneous tissue.
- Do not aspirate for subcutaneous injections; inject slowly and steadily.
- Rotate sites systematically (abdomen, thighs, upper arms) and move at least 2–3 cm from the previous site.
- Use aseptic technique; always use a new sterile needle and syringe for each injection.
Recommended Source
Why Amino Labs?
- Third-party tested: Each batch includes Certificate of Analysis (COA) verifying purity and composition.
- Consistent quality: ISO-aligned manufacturing and handling standards ensure reliable product integrity.
- Cold-chain integrity: Temperature-controlled shipping and storage throughout fulfillment process.
- Research-grade purity: Suitable for educational and research applications requiring high-quality peptides.
Note: Product availability and specifications subject to change. Verify current product details on supplier website.
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Important Note
This content is intended for therapeutic educational purposes only and does not constitute medical advice, diagnosis, or treatment.