The Development of Liposomes for Enhanced Delivery of Chemotherapeutics to Tumors

Abstract

Liposomes were first discovered in the 1960s by Bangham, who observed that ordered spherical membranes spontaneously formed when dried lipids were hydrated into aqueous solutions (1). The potential utility of these carrier systems for the delivery of therapeutic agents to disease sites has continually evolved since this initial observation. In order for liposomes to be considered as a viable pharmaceutical-delivery system, many issues needed to be resolved including efficient drug encapsulation, liposome stability, and the production of homogeneous liposome populations. These obstacles were overcome in the 1980s with the development of various liposome-production procedures including extrusion (2), dialysis (3), homogenization (4), and dehydration/rehydration techniques (5). Currently, the most commonly used process is extrusion due to its ease of usage, simplicity, speed, and reproducibility.