In vitro release of adriamycin from drug-loaded albumin and haemoglobin microspheres

Release of adriamycin from albumin and haemoglobin microspheres has been determined in vitro using a flow through system. Release from cross-linked albumin microspheres is controlled by the percentage of glutaraldehyde used but release profiles of spheres of 23, 41 and 60 μm diameter were virtually superimposable. Not all of the adriamycin is released from the microspheres over 20 h; as biodegradation occurs in vivo after 24 h the amount of drug remaining in the system at 20 h is likely to be principally released by degradation of the protein matrix in vivo. Estimates of the retained adriamycin vary from 16–26 per cent for albumin (n = 3) and 30 per cent for haemoglobin (n = 1).