Albumin microspheres as vehicles for the sustained and controlled release of doxorubicin

Biodegradable albumin microspheres have been prepared with the intention of targeting doxorubicin preferentially to tumour tissue. A high-yielding microsphere manufacturing process has been developed that involved the denaturation of an aqueous protein emulsion by chemical and/or thermal crosslinking methods. Microspheres can be closely sized to a diameter of 25.3 +/- 2.6 microns with the aid of micro-sieves. The in-vitro release of doxorubicin from albumin microspheres was measured using a continuous flow system. Doxorubicin release can be sustained for up to 10 days and the rate of release could be controlled by manipulating protein denaturation conditions between the temperatures 110-135 degrees C in the presence of 0-2% glutaraldehyde. Release of doxorubicin was significantly faster in human plasma compared with isotonic saline.