DepoFoam® Multivesicular Liposomes for the Sustained Release of Macromolecules

The recent advances in the development and commercialization of the Atrigel delivery system are presented in this chapter. This implantable depot technology was developed by Dunn and co-workers at Southern Research Institute in Birmingham, Alabama, in 1987 (1) and was subsequently licensed in toto to Vipont Research Laboratories (which became Atrix Laboratories, Inc. in 1989 and then QLT USA, Inc. in 2004). From a composition standpoint, the Atrigel Delivery System consists of a biodegradable polymer dissolved in a biocompatible carrier. An active pharmaceutical ingredient is incorporated into the delivery system and the resulting mixture is injected into the subcutaneous space or into a local site using a standard syringe and needle. After injection and upon contact with body fluids, the polymer precipitates and traps the drug in a solid implant. The drug is then released as the implant undergoes biodegradation.