North-Holland Magnetic fluids as drug carriers: Targeted transport of drugs by a magnetic field

Some important biomedical applications of various types of magnetically controlled rug carrier systems are presented. Model investigations of the possibility of using ferrofluids for drug localization in blood vessels and in hollow organs are described. The main factors that affect magnetic holding of a drop of ferrofluid on the tube wall in the stream of nonmagnetic fluid medium are investigated. 1. In t roduct ion One of the prerequisites for success in the application of chemotherapeutic agents for the treatment of localized diseases is the develop-ment of effective means of transporting the drug to the target site in an organism. In the mid-1970s a new concept of targeted rug delivery was in-troduced, based on the use of external magnetic systems and biocompatible ferromagnetic parti-cles as drug carriers [1,2]. The experiments performed in the 1980s in numerous biomedical research centers and clinics clearly indicate that most of the magnetic arrier systems investigated--both chemotherapeutic agents containing microspheres and ferrofluidic compositions--can be concentrated at predeter-mined sites using a sufficiently strong magnetic field [3]. At the same time, all these drug trans-portation systems have definite, very often con-troversial physical, physicochemical nd biochem-ical characteristics:- Particles in the magnetic fluid stabilized by biocompatible substances must have appropriate shapes and sizes (about several txm) in order to pass through the capillary systems of organs and tissues without posing the threat of vessel em-bolism