Liposomes are targeted drug delivery systems that are of great pharmaceutical and therapeutic interest.
Parenteral route is the main way used for liposome administration. In this case, their sterility is a requirement.
However, due to the particular sensitivity of liposomes and their tendency to physicochemical alterations, their
sterilization remains a real challenge. Conventional sterilization methods such as heat, ethylene oxide, ultraviolet
and gamma irradiations are considered as unsuitable for liposome sterilization and the recommended methods
for obtaining sterility of liposomes are filtration and aseptic manufacturing. Unfortunately, these recommended
methods are not without limitations.
This review outlines the difficulties associated with the use of these different classical methods for obtaining
liposome sterility. The effects on liposome physicochemical and biopharmaceutical characteristics as well as
efficacy, toxicity and practical problems of these sterilization techniques have been discussed. The search for an
alternative method being therefore necessary, the applicability of supercritical carbon dioxide (ScCO2) technology,
which is nowadays a promising strategy for the sterilization of sensitive products such as liposomes, is
also examined. It appears from this analysis that ScCO2 could effectively be an interesting alternative to achieve
sterility of liposomes, but for this, sterilization assays including challenge tests and optimization studies are
needed.

Liposome, Sterilization, Conventional methods, Supercritical carbon dioxide