A two-stage reverse dialysis in vitro dissolution testing method for passive targeted liposomes.

A novel two-stage reverse dialysis method has been developed for in vitro release testing of liposomal drug product with passive targeting characteristics. The first stage of the test is to mimic the circulation of liposomes in the body, whereas the second stage is to imitate the drug release process at the target. Buffer and surfactant solution were used during the first and second stages, respectively. For formulations containing high phase transition temperature lipids and high cholesterol content, no drug leakage was observed during the first stage of test. In the second stage, however, formulations with different compositions showed significant differences in terms of drug release rate, and discriminatory ability of the method was demonstrated. On comparing two different membrane diffusion techniques, dialysis and reverse dialysis methods, the reverse dialysis method showed significantly lower variation, and therefore is the preferred method. The developed in vitro release testing method should help to distinguish formulations with varied compositions for quality control testing purposes. This two-stage reverse dialysis method may pave the way to the development of more bio-relevant release testing methods for liposomal drug products.