Key Takeaway
Step-by-step instructions for reconstituting LL-37 peptide. Learn the correct bacteriostatic water ratio, mixing technique, and storage after reconstitution.
Quick Answer: To reconstitute LL-37, you add bacteriostatic water to the lyophilized (freeze-dried) powder using a sterile syringe. The standard approach is to add 1-2 mL of bacteriostatic water to a typical 5 mg vial, which yields a concentration of 2.5-5 mg/mL. Direct the water stream against the glass wall of the vial and let it dissolve naturally without shaking .
What You Need Before Starting
Gather all supplies before you begin. Working with a clean, organized setup reduces contamination risk and makes the process faster.
Required Supplies
- LL-37 lyophilized vial (typically 5 mg)
- Bacteriostatic water (BAC water) for injection, USP grade
- Sterile syringe (1 mL or 3 mL with needle)
- Alcohol swabs for sanitizing vial tops
- Insulin syringes (29-31 gauge) for drawing doses after reconstitution
Important Notes on Bacteriostatic Water
Always use bacteriostatic water, not sterile water or normal saline. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth and keeps the reconstituted solution safe for multiple uses over several weeks . Sterile water has no preservative and should only be used for single-dose vials that will be used immediately.
Step-by-Step Reconstitution Process
Step 1[1]: Clean Your Workspace
Wipe down your work surface with isopropyl alcohol. Wash your hands thoroughly with soap and water. Some practitioners prefer to use disposable gloves, though this isn't strictly required for personal use with proper hand hygiene.
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Step 2: Sanitize Both Vials
Use a fresh alcohol swab to clean the rubber stopper on both your LL-37 vial and your bacteriostatic water vial. Allow the alcohol to air dry for about 10 seconds before inserting a needle. This prevents introducing alcohol into the solution.
Step 3: Draw the Bacteriostatic Water
Using a sterile syringe, draw the desired amount of bacteriostatic water. For a 5 mg vial of LL-37:
| BAC Water Added | Concentration | Volume per 100 mcg Dose |
|---|---|---|
| 1 mL | 5 mg/mL (5,000 mcg/mL) | 0.02 mL (2 units on insulin syringe) |
| 2 mL | 2.5 mg/mL (2,500 mcg/mL) | 0.04 mL (4 units on insulin syringe) |
We recommend 2 mL for most patients. The slightly lower concentration makes it easier to measure accurate small doses with a standard insulin syringe. The 4-unit measurement for a 100 mcg dose gives you more precision than a 2-unit measurement.
Step 4: Add Water to the LL-37 Vial
Insert the needle through the rubber stopper of the LL-37 vial at a slight angle. Direct the stream of water against the glass wall of the vial, not directly onto the powder. This is critical. Spraying water directly onto the lyophilized cake can damage the peptide's structure and reduce potency .
Depress the syringe plunger slowly and steadily. Let the water trickle down the inside wall and pool at the bottom of the vial.
Step 5: Let It Dissolve
Don't shake the vial. LL-37 is a delicate peptide, and aggressive agitation can cause denaturation (unfolding of the peptide chain), which reduces or eliminates its biological activity . Instead:
- Gently swirl the vial in a slow circular motion
- Or simply let it sit at room temperature for 5 to 10 minutes
- Tilt the vial gently from side to side if needed
The powder should dissolve into a clear or very slightly hazy solution. If you see large particles that won't dissolve after 15 minutes of gentle swirling, don't use the vial. Contact your pharmacy for a replacement.
Step 6: Store Properly
Once reconstituted, immediately place the vial in the refrigerator at 36-46 degrees Fahrenheit (2-8 degrees Celsius). Don't freeze reconstituted LL-37. For full storage guidelines, see our LL-37 storage instructions guide.
Common Reconstitution Mistakes to Avoid
- Spraying water directly on the powder: Always aim for the glass wall. Direct force can damage the peptide.
- Shaking the vial: Gentle swirling only. Shaking creates foam and can denature the peptide.
- Using tap water or non-sterile water: Only bacteriostatic water for injection (USP) is appropriate.
- Skipping the alcohol swab step: Contamination is the most common reason reconstituted peptides go bad prematurely.
- Adding too much or too little water: Measure carefully. An incorrect concentration means incorrect dosing on every subsequent injection.
- Leaving the reconstituted vial at room temperature: Refrigerate immediately after mixing. LL-37 degrades faster at room temperature.
After Reconstitution: Drawing Your Dose
Once your LL-37 is reconstituted, here is how to draw an individual dose:
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Start Free Assessment →- Clean the vial stopper with an alcohol swab
- Using a fresh insulin syringe, pull back the plunger to draw in a small amount of air equal to your dose volume
- Insert the needle into the vial and push the air in (this equalizes pressure and makes drawing easier)
- Invert the vial and draw your dose slowly
- Tap the syringe gently to move any air bubbles to the top, then push them out
- Remove the needle from the vial
For injection technique, see our thorough LL-37 how to inject guide.
Frequently Asked Questions
How long does reconstituted LL-37 last?
When stored properly in the refrigerator and reconstituted with bacteriostatic water, LL-37 typically remains stable for up to 28 days. Some pharmacies may specify a shorter or longer dating. Always follow the guidance provided by your compounding pharmacy .
Can I use normal saline instead of bacteriostatic water?
Normal saline (0.9% sodium chloride) can dissolve the peptide, but it lacks a preservative. If you use normal saline, the vial must be used within 24 hours to avoid bacterial contamination risk. Bacteriostatic water is strongly preferred for multi-dose vials.
What if my LL-37 solution looks cloudy after mixing?
A slight haziness can be normal immediately after reconstitution. Give it 10 to 15 minutes. If the solution remains visibly cloudy, contains particles, or has changed color, don't use it. This may indicate degradation or contamination.
Do I need to reconstitute LL-37 myself?
Some compounding pharmacies dispense LL-37 pre-reconstituted and ready to inject. Others ship the lyophilized powder with bacteriostatic water for you to mix at home. When you work with FormBlends, your physician and pharmacy will provide clear instructions specific to your formulation.
Can I travel with reconstituted LL-37?
Yes, but you must keep it cold. Use an insulated travel case with ice packs. Avoid leaving the vial in a hot car or checked luggage where temperatures are uncontrolled. For air travel, carry it in your carry-on bag with your prescription documentation.
Medical References
- Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021;384(11):989-1002. [PubMed | ClinicalTrials.gov | DOI]
- Davies M, Færch L, Jeppesen OK, et al. Semaglutide 2.4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2). Lancet. 2021;397(10278):971-984. [PubMed | ClinicalTrials.gov | DOI]
- Wadden TA, Bailey TS, Billings LK, et al. Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy on Body Weight in Adults With Overweight or Obesity (STEP 3). JAMA. 2021;325(14):1403-1413. [PubMed | ClinicalTrials.gov | DOI]
- Rubino D, Abrahamsson N, Davies M, et al. Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity (STEP 4). JAMA. 2021;325(14):1414-1425. [PubMed | ClinicalTrials.gov | DOI]
- Garvey WT, Batterham RL, Bhatt DL, et al. Two-year effects of semaglutide in adults with overweight or obesity (STEP 5). Nat Med. 2022;28(10):2083-2091. [PubMed | ClinicalTrials.gov | DOI]
Need Help Getting Started with LL-37?
At FormBlends, we take the guesswork out of peptide therapy. Our physicians prescribe pharmaceutical-grade LL-37 from licensed compounding pharmacies, and our team walks you through every step, from reconstitution to injection to cycling.
Disclaimer: This article is for informational purposes only and doesn't constitute medical advice. LL-37 isn't FDA-approved for any medical condition. Always consult with a licensed healthcare provider before beginning any peptide therapy. Individual results may vary.