Liposomes as sterile preparations and limitations of sterilisation techniques in liposomal manufacturing

Abstract Liposomes have been widely researched as a delivery system and there have been many manufacturing techniques used in the production of liposomal preparations, the most common being extrusion method which will be introduced in this paper. However because of the unique properties of liposomes and their susceptibility to chemical and physical degradation, sterilisation remains an unresolved issue in the manufacturing of liposome-based formulations. It is especially pertinent in the pharmaceutical industry where liposomes are commonly prepared for intravenous administration. Currently, filtration and aseptic manufacturing are recommended for the preparation of sterile liposomal products. Newer aseptic manufacturing techniques such as dense gas techniques have been devised to eliminate the need for terminal sterilisation. This paper will highlight the limitations of the conventional techniques that are specific to the liposome preparation under the respective sterilisation conditions specified by the 2011 British Pharmacopoeia to achieve 10 −6 Sterility Assurance Level, as well as modifications incorporated in the newer sterilisation technologies to overcome these limitations. This paper will introduce these techniques in brief, including their advantages and limitations.