Peptide degradation is unglamorous and it is the most common reason laboratory results fail to reproduce. The underlying chemistry is well understood, and the handling practices that follow from it are straightforward.
Lyophilisation — freeze-drying — removes water under vacuum from frozen material, leaving a dry cake.
Water is the main enabler of peptide degradation. Removing it slows the principal breakdown routes dramatically, which is why lyophilised peptide stored correctly is stable over far longer periods than the same peptide in solution.
This is also why the sealed, unopened vial is the most stable state the material will be in, and why it is worth leaving it that way until needed.
Three routes account for most observed loss.
This is the most common avoidable cause of degradation in practice, and it is worth singling out.
Each freeze-thaw cycle stresses peptide in solution: ice crystal formation concentrates solutes locally and creates interfaces that promote aggregation. Repeatedly freezing and thawing one vial of stock solution degrades it considerably faster than the storage temperature alone would suggest.
The standard mitigation is to divide a reconstituted stock into single-use aliquots at the point of preparation, so each is thawed once. It costs a few minutes and removes the problem.
Light accelerates oxidative degradation, particularly for peptides with photosensitive residues and for complexes such as GHK-Cu where the coordinated metal is light-sensitive. Amber vials or storage in the dark address this.
Moisture is the other consideration, and it has a subtle failure mode: taking a cold vial directly into warm room air causes condensation on and in the vial, introducing exactly the water lyophilisation removed. Allowing a vial to equilibrate to room temperature before opening avoids it.
The general practices that follow from the chemistry are consistent across the literature: keep sealed lyophilised material frozen, protect it from light, let vials equilibrate before opening, reconstitute only what is needed, aliquot stock solutions rather than re-freezing one vial, and keep solutions refrigerated and use them promptly.
Specific conditions for any individual batch are stated on its own documentation, which takes precedence over general guidance. We publish handling and storage information only — not reconstitution volumes or administration guidance of any kind.
This article is reference material describing published research. It is not medical advice, not a therapeutic claim, and contains no dosing or administration guidance.