How long does reconstituted LL-37 last?

What the 28 days is counting

The 28 day figure attached to a refrigerated vial of LL-37 in bacteriostatic water is a handling convention for multi-dose vials. It is about the vial as a container that gets punctured repeatedly, not about the peptide molecule inside it.

Bacteriostatic water contains a preservative whose job is to suppress microbial growth after the stopper has been pierced. Every draw is a chance for something to get in. The preservative is what makes repeat access tolerable at all, and the window is roughly how long that suppression is treated as dependable under refrigeration.

This matters for how you count. The clock starts the day you add water, not the day you take your first draw. A vial mixed and then ignored for two weeks has spent two weeks of its window sitting still. There is no reset on first use.

Separately, the window says nothing about whether the peptide is intact. Sterility and stability are different questions with different failure modes, and nobody can tell you from the outside which one is running down in your vial.

Why warm costs so much more than you would guess

Compare the refrigerated row and the room temperature row in the table above. The drop is not gradual. Warmth attacks both halves of the problem at once: preservative effectiveness falls away faster, and any organism that does establish itself grows faster in a warm vial than a cold one.

The practical consequence is that time out of the fridge is not free, and it is not proportional. An hour on the counter is not an hour subtracted from 28 days. It is an hour drawn from a much shorter budget. This is the single most useful thing in the table.

That does not translate into a formula. We cannot give you a conversion rate between warm minutes and cold days, because none exists in any form we could verify. Treat the room temperature figure as a description of what happens when a vial lives warm, and treat brief handling as something to minimize rather than to account for.

The powder is the stable form

Unmixed LL-37 powder held in the fridge is described as lasting months to years. That is a different order of magnitude from anything the mixed vial gets, and the reason is simple: water is what enables most of the degradation pathways a peptide has, and there is no water in the powder.

The planning consequence is direct. If you hold several vials, mix one at a time. Reconstituting the whole set on the same day converts a stable inventory into several vials all running the same short clock, and any of them you do not finish is waste you created by mixing early.

For the powder specifically, the useful date is the vendor's, not yours. Months to years is a range, not a guarantee, and where a given vial sits in that range depends on how it was made, filled and shipped before it reached you.

What we do not know about LL-37

There is no reliable human pharmacokinetic data for LL-37 that this site can stand behind. That means we make no claim about its half life, how quickly it clears, whether it accumulates with repeated administration, or how long any effect would persist. Those questions are open here.

Keep that separate from the numbers above. The handling windows describe a vial sitting in a fridge. They are arithmetic and convention. They tell you nothing about what happens after material leaves the vial.

LL-37 is not approved by any regulator for human use. This page has no medical review. It does not tell you what dose to use, what to expect, what side effects occur, or whether any of this is safe or effective. Those are questions for a clinician who can see you.

Making the window usable

Write the mix date on the vial. Not the date you opened it, not the date you expect to finish it. The date water went in. Everything in the table is counted from that point, and a vial without that date on it is a vial whose position in the window you are estimating.

Match water volume to how fast you will use the vial. The listing volumes for LL-37 run from 1 mL to 3 mL, and the same vial diluted into more water gives you more volume to work through in the same fixed number of days. If the window closes before the vial empties, the extra water bought you nothing.

Finally, the window is an outer bound, not a verdict. A vial can fail earlier through a contaminated draw, a temperature excursion nobody noticed, or a defect that was there before you touched it. Visible cloudiness or particles are reasons to stop, and their absence is not proof of anything.

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

Does the 28 days start when I first draw from the vial?

No. It is counted from the day bacteriostatic water was added. First use does not restart or extend it. A vial mixed and then left unused still spends that time inside its window.

I left my mixed LL-37 vial out overnight. Is it ruined?

We cannot tell you. There is no verified conversion between time at room temperature and days lost from the refrigerated window, and no way to assess a specific vial remotely. The room temperature figure of 2 days is what applies to a vial that lives warm.

How long does LL-37 stay in the body?

We do not know. There is no reliable human pharmacokinetic data for LL-37 that this site can stand behind, so we make no claim about half life, clearance or accumulation. The windows on this page describe a vial in storage, nothing about what happens after administration.

Does using more water change how long the vial lasts?

No. The window is set by the preservative and the storage temperature, not by concentration. Water volume changes how much fluid you have to work through in the same fixed number of days, which affects waste rather than shelf life.

Should I mix all my vials at once?

Unmixed powder held in the fridge is described as lasting months to years, far longer than any mixed vial. Reconstituting several at once starts the short clock on all of them simultaneously. Mixing one at a time keeps the rest in their stable form.