Is 4 °C an acceptable storage condition for lyophilised cagrilintide?

What I am working with: 4 °C · cagrilintide.

This is asserted often enough that I assumed it was established, and then I went looking for the source.

I have searched the primary literature and found one paper that is adjacent but not on point.

Can anyone point me at a primary source, or confirm that there is not one?

Answering this needs the intended duration, since a fortnight and two years call for different arrangements.

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.

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.

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.

Equilibrate before opening or you condense water into the cake.

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.

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.

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.

The 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.

Nothing here is medical advice, and research-use compounds are not approved for human use.

Minus eighty buys very little over minus twenty for a dry solid.

edited 7 Jun 2025 by halvard_ness — reworded for clarity after a comment

This is the tag where the advice is cheapest to follow and most often ignored.

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.

Two-to-eight-degree refrigeration and minus-twenty freezing are the standard storage conditions for lyophilised peptides in supplier documentation across the market.

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

edited 22 Jun 2025 by Dr_Ingrid_Baumgartner — added the citation requested in comments