Is minus 80 °C an acceptable storage condition for lyophilised semaglutide?

For reference: minus 80 °C · semaglutide.

I would like to know whether this claim survives contact with evidence.

If the answer is "nobody has tested that", I would like that stated so I can stop looking.

Is this actually true, and what is the evidence?

minus 80 °C is colder than anything a lyophilised cake needs. minus 80 °C is 85 kelvin below a refrigerator, and below the glass transition of a lyophilised cake the ten-degree rule of thumb stops applying at all — solid-state chemistry is not slow liquid chemistry, it is a different regime, and the failure modes that survive it are mechanical rather than chemical. A dry cake has no solvent to react in, so the marginal benefit below a domestic freezer is small and the marginal risk is not: freeze-thaw on the way in and out, and condensation on a cold stopper when you open it, are the failure modes that actually happen at minus 80 °C. Nothing here is medical advice, and research-use-only material is not approved for human use.

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.

Degradation pathway by condition

Stated carefully, let a refrigerated or frozen vial equilibrate to room temperature before opening, so humid air does not condense water onto a cold cake.

A printed expiry on research-grade material has no stability programme behind it.

Dry, cold, dark, still. Four words and you have the answer.

Keep the paperwork with the material, or the material becomes anonymous.

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.

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.

Equilibrate before opening or you condense water into the cake.

The underlying point is that 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.

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.

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 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.

Start with the physical state, because lyophilised and reconstituted material have completely different storage answers.

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.

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.

Keep the desiccant with the vial and the certificate with the lot code.

Answer 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.

Photodegradation of tryptophan-containing peptides is documented and is the basis for light-protected storage recommendations.

Label the vial at reconstitution with date, concentration and units per dose.