Lyophilisation

Freeze-drying: removing water from a frozen solution by sublimation under vacuum, leaving the stable solid cake or powder in which peptides are shipped and stored.

Lyophilisation freezes a solution and then lowers the surrounding pressure so that the ice sublimes — passing directly from solid to vapour — without the material ever melting. What remains is a porous solid cake or powder from which nearly all water has been removed. For peptides, whose chief degradation pathways run through water, this is the difference between a shelf life measured in days and one measured in years.

Hydrolysis, deamidation and aggregation all require molecular mobility that a dry solid denies. A lyophilised peptide held sealed and cold degrades orders of magnitude more slowly than the same peptide in solution, which is why compounds are supplied dry and reconstituted only when needed. The stability clock effectively restarts — and runs much faster — at the moment of reconstitution.

The process is thorough but not absolute: a few percent of tightly bound residual moisture typically survives, measurable by Karl Fischer titration, and it counts toward the powder's gross weight. The cake's appearance — intact, collapsed, or partially melted — also carries information, since collapse can indicate the material saw temperatures or moisture it should not have.

For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice.