Setup, so nobody has to ask: 25 °C · mazdutide.
This has the shape of a fact but I cannot find its origin.
What I found instead were three secondary sources all citing each other.
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.
The relevant practical failure is not chemical at all: it is losing the link between a vial and its certificate when the box gets thrown away.
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.
| 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.
Let a refrigerated or frozen vial equilibrate to room temperature before opening, so humid air does not condense water onto a cold cake.
Residual moisture is the dominant determinant of solid-state stability, which is why desiccants accompany lyophilised material.
Appearance does not indicate stability; a normal-looking cake can be substantially degraded.
Keep the desiccant with the vial and the certificate with the lot code.
HPLC purity, identity confirmation and quantified content on the vial you actually hold. Reports arrive with the chromatogram attached, not just a number.
Submit a sampleFounded 1998. ISO 9001 and cGMP certified, 1,500+ staff and 200+ patents. The synthesis house behind a great many of the vials that get sent out for testing - batch-specific documentation with every order.
Visit GL BiochemThe short version: powder in the freezer or fridge, reconstituted in the fridge for weeks, and never anything on a windowsill.
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 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.
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.
edited 31 Jul 2024 by Dr_Wren_Halliday — removed a claim I could not source
The honest answer is that ordinary refrigeration handles almost every case people ask about.
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.
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.
Equilibrate before opening or you condense water into the cake.
Worth being precise here: 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.
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.
Dry, cold, dark, still. Four words and you have the answer.
Start with the physical state, because lyophilised and reconstituted material have completely different storage answers.
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.
Two-to-eight-degree refrigeration and minus-twenty freezing are the standard storage conditions for lyophilised peptides in supplier documentation across the market.
Label the vial at reconstitution with date, concentration and units per dose.
edited 2 Jun 2024 by low_dead_space — updated for the 2026 guidance change
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.