Residual Solvents in Nanomedicine and Lipid-Based Drug Delivery Systems: a Case Study to Better Understand Processes

Complexities surrounding the manufacture and quality control of nanomedicines become increasingly apparent. This research article offers a case study to investigate how, at the laboratory scale, various stages of liposome and nanoparticle synthesis affect the amount of residual solvent found in the formulations. The objective is to bring insights on the reliability of each of these processes to provide final products which meet regulatory standards and facilitate identifying possible bottleneck early during the development process. The residual solvent at various stages of preparation and purification was measured by headspace gas chromatography. Liposomes were prepared by two different methods with and without solvent. Polymer nanoparticles prepared via nanoprecipitation and purified by ultrafiltration were studied. The effects of purification by size exclusion chromatography and dialysis were also investigated. The complete removal of residual solvent requires processes which go beyond usual preparation methods. This work might prove valuable as a reference for scientists of different fields to compare their own practices and streamline the translation of nanomedicines into efficacious and safe drug products.