Step 2 — Precision Lyophilization (Freeze-Drying) Process

Lyophilization is a controlled dehydration process that removes water from a frozen product by sublimation (direct transition from ice to vapor under vacuum) rather than conventional evaporation. It is the standard method for producing stable, long-shelf-life peptide formulations.

• Freezing Stage: The aqueous peptide solution is cooled to well below its eutectic or glass-transition temperature (typically −40 °C to −50 °C or lower). This solidifies water into ice crystals and concentrates the peptide and solutes into a glassy or crystalline matrix. Controlled freezing rates produce a favorable ice structure that allows efficient vapor flow.
• Primary Drying (Sublimation): Under high vacuum (usually 50–200 mTorr) and product temperatures held below collapse temperature, heat is applied to shelves. Ice sublimes directly into water vapor collected on a cold condenser, removing typically 90–95% of the original freezable water over several hours to days depending on fill volume, cake thickness, and formulation.
• Secondary Drying (Desorption): Shelf temperature is raised (often to 20–40 °C) while maintaining vacuum to desorb residual bound unfrozen water. This reduces residual moisture to a commonly targeted level of <1–3%, supporting long-term chemical, structural, and pH stability.