Dexamethasone-loaded magnetic albumin microspheres: Preparation and in vitro release

Magnetic albumin microspheres containing nearly 13% w/w dexamethasone were prepared. Two separate studies were carried out to investigate: (a) the responsivity of these microspheres in a 8000 G magnetic field in a flow rate (0.5 cm/s) equal to that of the blood flow rate in capillaries; (b) the in vitro release profile of dexamethasone from magnetic albumin microspheres up to 7 h after dispersion in normal saline medium, using a USP dissolution apparatus. The results obtained suggest that the retention of microspheres in the presence of the magnetic field for 15 min was significantly (P < 0.05) more than those in the absence of the magnetic field. Drug release in the first hour was found to increase and then reached a maximum. After 7 h: approximately 30% of the total drug content of microspheres was released. A third order equation for the drug release was also calculated. From this study, it is suggested that magnetic albumin microspheres could be retained at their target site in vivo, following the application of a magnetic field, and are capable of releasing their drug content for an extended period of time. This would make them a suitable depot for delivering chemotherapeutic agent(s) in vivo.