In situ forming drug delivery systems based on lyotropic liquid crystalline phases: structural characterization and release properties

This contribution will focus on recent advances in the formulation, the nanostructural characterization, the drug release properties, and the potential utilization of highly viscous inverted type non-lamellar liquid crystalline phases in pharmaceutical applications. In particular, these hierarchical complexes attracted increasing attention in designing efficient injectable drug delivery systems with unique properties including the high interfacial area for the accommodation of drugs, the possible controllable release of solubilized drugs, and the stability of these self-assembled nanostructures against dilution in the biological environment. In an interesting approach, these unique properties can be exploited to form in situ cubic and hexagonal delivery systems with sustained drug release properties at the administration site in response of injectable low-viscous stimulus-responsive precursors (drug preformulations) to the biological environmental stimuli. Greater focus than to date should be placed in future studies on combining the dynamics of the structural transitions of these flowable precursors upon direct exposure to the biological environment with relevant in vitro and in vivo investigations.