Abstract
New concept of inflammation responsive drug delivery system by biodegradable hydrogels of hyaluronic acid (HA) is reviewed. HA has been well known to be degraded specifically by the presence of hydroxyl radicals, which are produced locally at an inflammatory site. Our system is established by constructing a heterogeneous-structured device of drug microreservoirs (lipid microspheres) dispersed into the degradable matrices of crosslinked HA gel. The most attractive characteristics of this device are : (1) to performe the release of lipid microspherers in proportion to surface-controlled degradation of crosslinked HA gels, and (2) to be quantitatively inflammation-responsive degradable. These unique features of the device are favorable to regulated drug delivery to several inflammatory related diseases, where lipid microspheres can be released in response to inflammation-induced degradation although being stable under normal health conditions.
