ABSTRACT
The unique concepts for improving the physical stability of liposomes and to provide special characteristics on liposomes include polymerized liposomes and microencapsulated liposomes. In the usual preparation procedure for polymerized liposomes, monomeric liposomes that entrap the substance of interest are first assembled from polymerizable phospholipid through a conventional method, and polymerization is carried out subsequently. When polymerized liposomes are administered into the body as a drug carrier, biodegradability and biocompatibility are required. Introduction of disulfide bonds as the polymer linkage was proposed for achieving biodegradability. An interesting application of polymerized liposomes is as an oral drug carrier. Oral dosage is one of the most convenient routes for drug administration. A preliminary examination was performed in vitro to investigate the feasibility of polymerized liposomes as an oral drug-carrier system. Studies are needed to examine the effects of changing size or surface characteristics, such as electrostatic charge and hydrophobicity, of the polymerized liposomes on their fate after oral delivery.
