ELSEVIER International Journal of Pharmaceutics 130 (1996) 49 55 international journal of pharmaceutics Dexamethasone-loaded magnetic albumin microspheres: preparation and in vitro release Sussan Ghassabian, Turaj Ehtezazi, Seyed Mohsen Forutan, Seyed Alireza Mortazavi* School of Pharmacy, Department of Pharmaceutics, Shaheed Beheshti University of Medical Sciences, Tehran Iran Received 10 October 1994; revised 22 June 1995; accepted 7 July 1995 Abstract 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. Keywords: Magnetic albumin microspheres; Dexamethasone; In vitro release; Magnetite; Drug delivery; Targeting 1. Introduction In recent years, considerable interest has been shown in the use of albumin microspheres as platforms for active drug targeting as well as producing a sustained and controlled rate of drug release (Morimoto et al., 1981; Widder and Seneyei, 1983; Gallo and Gupta, 1989). In the previous studies, a phase separation * Corresponding author. emulsion technique was developed for the prepa- ration of the microspheres. Stabilization of the albumin microspheres matrix was accomplished by either heat denaturation at various tempera- tures (110-190°C) or crosslinking with carbonyl compounds in an ether phase reaction. The degree of stabilization controls the rate of drug diffusion out of the carrier as well as the extent of carrier degradation (Widder et al., 1980). Magnetic albumin microspheres are capable of being retained in the capillaries by using extracor- poreal magnets. Electron microscopic studies of 0378-5173/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved SSDI 0378-5173 (95)04255 - 2