How to reconstitute LL-37

What the concentration table is telling you

The table pairs each vial size sold, 5 mg and 10 mg, with each of the water volumes commonly used, 1 mL, 2 mL and 3 mL. The output is concentration in mg/mL. That is the only thing reconstitution decides. The peptide mass in the vial does not change when you add water, so the water volume does not change how much LL-37 you own. It changes how spread out that mass is, and therefore how many millilitres you draw for a given milligram figure.

Notice that two setups land on the same number. A 5 mg vial in 1 mL and a 10 mg vial in 2 mL both read 5 mg/mL. Concentration is a ratio, so doubling both mass and water leaves it unchanged. Switching between those two setups does not change the volume you draw for the same milligram figure, even though one vial holds twice as much.

More water always means lower concentration and a larger draw for the same dose. That is the trade. A thinner solution puts small doses further along the syringe barrel, which is easier to read. A concentrated solution puts each dose in a very small volume, where a small misread of the plunger is a larger proportional error.

The 3 mL rows are rounded. Neither 5 nor 10 divides cleanly by 3, so the table shows 1.67 mg/mL and 3.33 mg/mL. The rounding is harmless, but it is one reason 1 mL and 2 mL are often preferred: the concentration is a whole or half number and the mental math is trivial.

Mixing the vial

Bacteriostatic water is water with a preservative in it. Sterile water and saline are different products and do not contain that preservative. This page does not tell you which diluent to use or whether any of them is safe for you. That is a clinical question and this site has no medical review.

Mechanically the sequence is the same for any peptide vial. Wipe the stopper of both the peptide vial and the water vial with alcohol and let them dry. Draw your chosen water volume, insert the needle through the peptide stopper at an angle, and let the stream run down the inside glass wall rather than firing directly onto the powder. Lyophilized peptide is a fragile solid and a direct jet can damage it.

Do not shake. Swirl gently, or set the vial down and let it dissolve. Shaking creates foam and mechanical stress at the air-liquid boundary, which is the failure mode you are trying to avoid. Then write the water volume on the vial. Concentration is not visible by looking at the liquid, and an unlabeled vial is one whose arithmetic you cannot reconstruct later.

Turning milligrams into syringe volume

Once concentration is fixed, the conversion is one division. Volume in millilitres equals the dose in milligrams divided by the concentration in mg/mL. Nothing about the peptide enters that step; it is the same arithmetic you would use for any solute.

Insulin syringes are marked in units rather than millilitres. Read the millilitre figure off your division, then convert it using the scale printed on the barrel of the U-100 syringe you are holding. The two-step read is division first, unit conversion second.

The milligram figures that appear in LL-37 listings are 0.1 mg, 0.25 mg and 0.5 mg. Those are listing figures, not recommendations, and this page does not tell you which one applies to anyone. Run whichever figure you are working from through the division above, using the concentration your own vial produced.

One consequence is worth stating plainly. The smaller the milligram figure and the more concentrated the vial, the smaller the volume on the barrel. Small volumes on widely spaced marks are where measurement error lives. If a figure lands between marks, the fix is a different water volume, not squinting.

What this page does not answer

LL-37 is not approved by any regulator for human use. It is sold as a research chemical, and that status is why so little about it is settled.

We hold no reliable human pharmacokinetic data for LL-37. This site therefore makes no claim about its half life, how long it takes to clear, whether it accumulates with repeated use, or how any of that would interact with a dosing interval. Anyone presenting a timing schedule for this compound as established is going beyond what the data supports.

We also do not tell you what dose to use, what to expect, what side effects occur, or whether it is safe or effective. Those are medical questions. Every number here is concentration and volume arithmetic, verifiable by division and nothing more.

What we do not know

We hold no reliable human pharmacokinetic data for LL-37, so this site makes no claims about its half life, how long it takes to clear, or how it accumulates. The arithmetic below concerns concentration and volume only.

This page answers arithmetic and handling questions. It does not tell you what dose to take, what to expect, or whether anything is appropriate for you, and there is no medical review behind it.

Common questions

How much bacteriostatic water should I add to a 5 mg LL-37 vial?

The volumes in common use are 1 mL, 2 mL and 3 mL, and the table shows what each produces. A 5 mg vial in 1 mL gives 5 mg/mL, and adding more water lowers the concentration proportionally. This page does not recommend one volume over another.

Does adding more water make the dose weaker?

No. The vial holds the same mass of peptide regardless of how much water you add. More water lowers the concentration, so you draw a larger volume for the same number of milligrams. The milligram figure is what you control; volume is only how it is expressed on the syringe.

Why do the 3 mL rows show 1.67 and 3.33 mg/mL?

Those are rounded. Neither 5 nor 10 divided by 3 gives a clean decimal, so the table truncates the repeating figure. The rounding does not matter for practical arithmetic, but it is one reason 1 mL and 2 mL are often preferred.

Can I use sterile water or saline instead of bacteriostatic water?

They are different products. Bacteriostatic water contains a preservative; sterile water and saline do not. Whether a given diluent is appropriate is a clinical question, and this site has no medical review and does not answer it.

How long does LL-37 stay active in the body?

We do not know, and this page will not guess. There is no reliable human pharmacokinetic data for LL-37, so no claim about half life, clearance or accumulation can be made honestly. The arithmetic here covers concentration and volume only.