Lyophilisation (Freeze-Drying)
A preservation process removing water from a frozen peptide solution under vacuum. The resulting dry powder has greatly improved shelf stability compared to liquid formulations. Most research peptides and many approved drugs (octreotide, tesamorelin, degarelix) are supplied in lyophilised form.
Technical Context
Lyophilisation process steps: (1) formulation (peptide dissolved with excipients in water at target concentration/pH), (2) fill (aseptic filling into vials — critical step under ISO 5 cleanroom conditions), (3) freezing (controlled cooling to -40 to -60°C — cooling rate affects ice crystal size and cake morphology; annealing steps may be included to optimise crystal structure), (4) primary drying (sublimation — chamber pressure reduced to 50-200 mTorr, shelf temperature raised to -20 to -10°C; ice sublimes directly to vapour; duration 24-72 hours for typical peptide products), (5) secondary drying (desorption — shelf temperature raised to +20 to +40°C to remove residual unfrozen water; target <1-2% residual moisture), (6) stoppering (under controlled atmosphere, typically nitrogen), and (7) capping. Process parameters (shelf temperature, chamber pressure, ramp rates) must be optimised for each formulation. Cake appearance (elegant, uniform cake vs collapse, shrinkage, or meltback) is an important quality indicator.