Encyclopedia entry
Peptide storage and handling
Most research peptides arrive lyophilised (freeze-dried) as a white powder under partial vacuum in a sealed glass vial. In this state, peptides are reasonably stable at room temperature for short transit and substantially more stable when refrigerated or frozen. Once reconstituted with a solvent (typically bacteriostatic water for research handling), stability drops sharply.
Why peptides ship lyophilised
Water is the main driver of peptide degradation. Freeze-drying removes the water and locks the peptide in a stable amorphous state. Lyophilised peptides typically survive 24 to 48 hours at ambient temperature with negligible degradation, which makes ordinary UK courier delivery practical. Without lyophilisation, peptides would require refrigerated transit and have far shorter shelf lives.
Lyophilised storage
- · Refrigerated (2 to 8°C): typically stable for 6 to 12 months for most peptides.
- · Frozen (minus 18°C or colder): often stable for 12 to 24 months.
- · Room temperature: stable for short periods (days to weeks), then progressive degradation.
Reconstituted storage
- · Refrigerated (2 to 8°C): typically stable for 14 to 28 days for most research peptides.
- · Cannot be frozen once reconstituted (ice crystal formation damages peptide structure).
- · Cannot be left at room temperature for extended periods.
- · Bacteriostatic water (containing 0.9% benzyl alcohol) suppresses microbial growth in the vial during the storage window.
Cold-chain for GLP-1 medications
Licensed GLP-1 medications (Wegovy, Mounjaro, Saxenda) are pre-filled pen injectors that ship under cold chain (2 to 8°C). Once in the user\'s fridge, they remain stable for the labelled shelf life. Once at room temperature, the manufacturer-specified out-of-fridge window is typically 4 to 6 weeks depending on the medication. UK pharmacies dispensing GLP-1 maintain validated cold-chain logistics; this is one of the GPhC requirements.
Related: research peptides hub · UK pharmacies.