Conditions: 4 °C · oral semaglutide.
I want to know whether there is evidence behind this or only repetition.
I have checked the obvious registries and monographs without success.
Is there data behind this, or is it received wisdom?
4 °C is inside or near the refrigerated band. 4 °C is the condition the rule of thumb is anchored to, so it is the baseline rather than a multiplier: everything else in this thread is quoted relative to it. That is the condition most lyophilised peptide is specified at, so the useful question moves to what happens after reconstitution, where the same temperature buys far less. Nothing here is medical advice, and research-use-only material is not approved for human use.
This is the tag where the advice is cheapest to follow and most often ignored.
Reconstituted with a preservative-containing diluent: refrigerated, conventionally treated as usable for about 28 days from first entry. Without a preservative, single use and discard.
| State | Condition | Usable window | Basis |
|---|---|---|---|
| Lyophilised solid | −20 °C, sealed, dry | 24–36 months | Supplier guidance |
| Lyophilised solid | 2–8 °C, sealed | 12–24 months | Supplier guidance |
| Lyophilised solid | 25 °C, sealed | 4–8 weeks | Extrapolated (Arrhenius) |
| Lyophilised solid | 40 °C, sealed | 1–2 weeks | Extrapolated |
| Solution, preserved | 2–8 °C | 28 days | USP microbiological convention |
| Solution, preserved | 25 °C | 3–7 days | Extrapolated |
| Solution, unpreserved | 2–8 °C | 24 hours | USP microbiological convention |
Windows for the solid state are chemical; windows for solution are microbiological and usually shorter than the chemical limit.
Label the vial at reconstitution with the date, the concentration and the resulting units per dose. This is the single most useful thirty seconds in the whole process.
Photodegradation of tryptophan-containing peptides is documented and is the basis for light-protected storage recommendations.
A printed expiry on research-grade material has no stability programme behind it.
Keep the desiccant with the vial and the certificate with the lot code.
Analytical standards and reagents with traceable certificates. Every quantitative result you read inherits the accuracy of the standard behind it.
Shop standardsAnswer first: dry, cold, dark and still, with the lot code where you can still read it in a year.
Store with the desiccant sachet if one was supplied, inside the secondary container rather than loose in a drawer. Residual moisture is the dominant variable in solid-state stability.
On the detail: let a refrigerated or frozen vial equilibrate to room temperature before opening, so humid air does not condense water onto a cold cake.
Appearance does not indicate stability; a normal-looking cake can be substantially degraded.
Dry, cold, dark, still. Four words and you have the answer.
Answering this needs the intended duration, since a fortnight and two years call for different arrangements.
Position matters less than people think: upright or on its side makes no difference to a lyophilised powder, and upright is marginally better for a reconstituted vial because it keeps the stopper dry.
Keep the certificate with the vial, physically or as a photograph filed under the lot code. A vial without a traceable certificate is an anonymous vial regardless of where it came from.
Two-to-eight-degree refrigeration and minus-twenty freezing are the standard storage conditions for lyophilised peptides in supplier documentation across the market.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Label the vial at reconstitution with date, concentration and units per dose.
The honest answer is that ordinary refrigeration handles almost every case people ask about.
Keep vials in their original carton or in an opaque box. Light exposure matters for tryptophan-containing sequences and for anything with a chromophore, and a closed box is free.
Residual moisture is the dominant determinant of solid-state stability, which is why desiccants accompany lyophilised material.
Equilibrate before opening or you condense water into the cake.
edited 28 Aug 2024 by loss_on_drying — added the citation requested in comments
Start with the physical state, because lyophilised and reconstituted material have completely different storage answers.
Lyophilised powder: refrigerated at two to eight degrees for months, frozen at minus twenty for longer. The gain from minus eighty over minus twenty is small for a dry solid and is not usually worth the arrangement.
The 28-day in-use period for preservative-containing multi-dose preparations is printed on the diluent labelling and is a long-standing pharmacy convention.
The caveat is that storage conditions preserve what you have and cannot improve it.
Minus eighty buys very little over minus twenty for a dry solid.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.