The case in front of me: 25 °C · tirzepatide.
I want to know whether there is evidence behind this or only repetition.
I have checked the obvious registries and monographs without success.
Can anyone point me at a primary source, or confirm that there is not one?
25 °C is above the refrigerated band, and how far above is the whole answer. 25 °C is 20 kelvin above the 5 °C middle of a 2–8 °C refrigerator. The ten-degree rule of thumb — degradation rate roughly doubling per 10 K — makes that about 4 times the refrigerated rate, which is an order-of-magnitude statement and not a shelf life. Lyophilised material tolerates this far better than solution does, which is why it is shipped that way, but "tolerates" is a statement about weeks and the vial is being asked about months. Log the excursion rather than guess at it. Nothing here is medical advice, and research-use-only material is not approved for human use.
Start with the physical state, because lyophilised and reconstituted material have completely different storage answers.
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.
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.
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.
edited 11 Aug 2025 by zainab_mustafa — fixed an arithmetic slip in the third paragraph
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe honest answer is that ordinary refrigeration handles almost every case people ask about.
Let a refrigerated or frozen vial equilibrate to room temperature before opening, so humid air does not condense water onto a cold cake.
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.
Appearance does not indicate stability; a normal-looking cake can be substantially degraded.
Label the vial at reconstitution with date, concentration and units per dose.
Keep the paperwork with the material, or the material becomes anonymous.
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.
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.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Dry, cold, dark, still. Four words and you have the answer.
The underlying point is that this is the tag where the advice is cheapest to follow and most often ignored.
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.
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.
The relevant detail is that desiccant matters more than the last few degrees of cold for a lyophilised powder.
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.
Photodegradation of tryptophan-containing peptides is documented and is the basis for light-protected storage recommendations.
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.