How you store research peptides determines how long they stay usable. The two states — lyophilised (freeze-dried powder) and reconstituted (dissolved in solution) — have completely different storage requirements. Getting this wrong degrades the compound before it reaches your experiment.
Lyophilised Peptides
Lyophilised peptides are stable at room temperature for short periods during shipping, but long-term storage requires cold. The standard is −20°C for most research peptides. At this temperature, sealed vials remain stable for 12–24 months depending on the compound. Some peptides — particularly those with disulfide bonds like oxytocin — benefit from −80°C storage for extended periods.
Three things degrade lyophilised peptides faster than temperature: moisture, repeated freeze-thaw cycles, and light. Keep vials sealed until use. If you must access a vial multiple times, use a desiccant in the freezer storage container. Let vials reach room temperature before opening to prevent condensation forming on the powder.
Reconstituted Peptides
Once you dissolve a peptide in bacteriostatic water, the clock starts. Reconstituted peptides stored at 2–8°C are typically stable for 28 days. This assumes you used sterile bacteriostatic water — the 0.9% benzyl alcohol prevents microbial growth and is the reason BAC water extends shelf life versus plain sterile water.
Do not freeze reconstituted peptides if you can avoid it. Freezing and thawing a solution can cause aggregation and degradation, particularly with larger peptides like GLP-1 analogues. If you must store a reconstituted solution beyond 28 days, aliquot into single-use volumes before freezing.
Compound-Specific Notes
GLP-1 analogues (Semaglutide, Tirzepatide, Retatrutide, Cagrilintide): Sensitive to temperature fluctuations. Store lyophilised at −20°C. Avoid repeated freeze-thaw of reconstituted solutions.
BPC-157, TB-500: Relatively stable. Lyophilised storage at −20°C is standard. Reconstituted solutions tolerate up to 28 days at 2–8°C.
NAD+: Hygroscopic — absorbs moisture from air quickly. Keep sealed until use. Store at −20°C.
GHK-Cu: The copper-binding group makes it more stable than most. Lyophilised storage at −20°C, reconstituted at 2–8°C for up to 28 days.
Summary: Storage by State
Lyophilised, sealed: −20°C, stable 12–24 months. Reconstituted in BAC water: 2–8°C, use within 28 days. Reconstituted in sterile water: 2–8°C, use within 3–5 days. All peptides: avoid light, moisture, and repeated temperature changes.
Frequently Asked Questions
Can I store reconstituted peptides in the freezer?
You can, but it risks aggregation on thawing. If you must, aliquot into single-use volumes first so each portion only thaws once.
What happens if a peptide gets warm briefly during shipping?
Most lyophilised peptides tolerate brief room temperature exposure during transit without significant degradation. The issue is repeated or prolonged heat exposure.
Does bacteriostatic water matter for storage?
Yes. The benzyl alcohol in BAC water inhibits microbial growth, extending reconstituted peptide stability to 28 days. Plain sterile water is only stable for 3–5 days once opened.
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