Liposome-collagen gel matrix: a novel sustained drug delivery system

This report describes the properties of a novel sustained-release drug delivery system comprising liposomes sequestered in a collagen gel. Two peptide hormones, insulin and growth hormone encapsulated in vesicles sequestered within the matrix, are slowly released into the circulation from either an intramuscular or subcutaneous injection site. A maximum 3-5-d release for insulin or a 14-d growth hormone release was observed. Enhanced sequestration of liposomes with the collagen can be achieved by modifying the liposome surface with fibronectin. The liposome gel delivery system appears to offer several advantages over other liposome formulations or gel formulations constructed only with free drug.