Elastic liposomes for topical and transdermal drug delivery

Elastic liposomes have been developed and evaluated as novel topical and transdermal delivery systems. They are similar to conventional liposomes but with the incorporation of an edge activator in the lipid bilayer structure to provide elasticity. Elastic liposomes are applied non-occluded to the skin and have been shown to permeate through the stratum corneum lipid lamellar regions as a result of the hydration or osmotic force in the skin. They have been investigated as drug carriers for a range of small molecules, peptides, proteins and vaccines, both in vitro and in vivo. Following topical application, structural changes in the stratum corneum have been identified and intact elastic liposomes visualised within the stratum corneum lipid lamellar regions, but no intact liposomes have been identified in the deeper viable tissues. The method by which they transport their drug payload into and through the skin has been investigated but remains an area of contention. This chapter provides an overview of the development, characterisation and evaluation of elastic liposomes for delivery into and via the skin.