The process has three phases. First the solution is frozen. Then, in primary drying, a vacuum and a little heat are applied so the ice turns directly from solid to vapour without melting. Finally, in secondary drying, the water that remained bound to the molecules is removed.
Almost all the reactions that degrade a peptide (deamidation, hydrolysis, many oxidations) need water. Removing it leaves the peptide chemically “paused”. That is why a well-sealed freeze-dried peptide protected from moisture and light can keep far longer than the same peptide in solution.
The typical appearance is a white cake or powder at the bottom of the vial. A cracked or loose cake does not usually mean a problem; a wet, collapsed or yellowish one may.
The stability of a freeze-dried peptide ends the moment it is reconstituted: from then on it is back in solution and starts to degrade. That is why storage conditions before and after reconstitution are different.
Related terms
Learn it in depth at the Peptide University
- Lyophilization and excipients · Module 11
- Stability and storage · Module 9
- Reconstitution and aseptic technique · Module 9
- Peptide content, water, counterion and reading the COA · Module 7
- The lyophilized form and its diluents · Module 8
Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).