Why peptides can degrade
Peptide bonds and side chains can undergo chemical changes over time. Heat, repeated temperature cycling, oxidation, moisture and light may accelerate those processes depending on the sequence and formulation.
Dry powder is not the same as solution
Lyophilization can improve shelf stability by removing water, but it does not make every peptide indefinitely stable. Once a peptide is in solution, degradation pathways can change substantially.
Why one rule does not fit every peptide
A validated medicine may contain buffers, stabilizers or preservatives that change its stability profile. A research vial with a similar peptide name is not automatically equivalent.
What AEVLI recommends
Use manufacturer or regulator-backed storage instructions where they exist, keep records of dates and storage conditions, and be cautious of forum claims that assign a universal shelf life to all peptides.