Chemical stability of liposomes: implications for their physical stability.

In the first part of this article, chemical and physical stability of aqueous liposome dispersions have been addressed. Chemical stability of phospholipids has been considered in two parts: oxidation and hydrolysis. Major attention has been paid to hydrolysis kinetics of phospholipids as a function of pH, temperature, buffer concentration and ionic strength. Furthermore, the effect of chain length, head group, state of aggregation, addition of cholesterol and presence of charge on the hydrolysis kinetics of phospholipids has been dealt with. In the second part physical stability of chemically degraded liposome dispersions has been evaluated. In the final part quality control assays for liposome dispersions is presented and a HPLC method with a refractive index detector for the analysis of phospholipids from aqueous liposome dispersions is described.