Pilot scale transfer and optimization of an innovative supercritical CO2 PGSS method for the production of drug-encapsulating liposomes.

The industrial translation of liposome production processes remains challenging, particularly in achieving scalability while maintaining critical quality attributes and formulation stability. In this study, a supercritical CO2-based PGSS process was successfully transferred from the laboratory to the pilot scale (50 to 500 mL reactor). Using a Quality by Design approach and a design of experiments on a simplified soy phosphatidylcholine formulation, we identified optimal production process parameters. These parameters were then validated and transferred to other drug-encapsulating liposome formulations, demonstrating process robustness. Under these conditions, liposomes measuring less than 200 nm and polydispersity indices close to 0.30 were reproducibly obtained at pilot scale. The process was successfully applied to drug-loaded formulations, achieving high encapsulation efficiencies while maintaining suitable physicochemical properties. Cryo-TEM confirmed the formation of consistent vesicular structures. Importantly, lipid chemical stability was preserved, with minimal hydrolysis and no significant increase in oxidation, even for unsaturated lipids. Overall, this study demonstrates the robustness, scalability, and relevance of the PGSS process as a solvent-free, single-step technology for liposome production.