Characterisation of freeze-dried albumin microspheres containing the anti-cancer drug adriamycin

Information regarding in vitro characteristics and in vivo behaviour of microspherical drug delivery systems in animal models has accumulated and many have been developed to the stage of clinical assessment. A vital requirement for clinical trial is a stable product with a long shelf-life and reproducible properties. Thus, we have investigated whether adriamycin-loaded albumin microspheres can be freeze-dried without deterioration of important characteristics. The following properties of this delivery system were compared in the freeze-dried and freshly prepared state: particle size and state of aggregation (by Coulter Counter); drug content (by HPLC) and drug release rate (in a flow-through system). It was observed that freeze-drying and subsequent storage of adriamycin-loaded albumin microspheres resulted in no substantial difference in these properties compared to freshly prepared product. Thus, the freeze-dried product, with its considerable advantages as regards prolonged storage, appears suitable for clinical use.