Magnetic activated release of umbelliferone from lipid matrices.

Lipid matrices containing dispersed superparamagnetic iron oxide (SPIO) particles were investigated as a magnetic field-responsive drug delivery system. Lipid matrices were prepared by combining myristyl alcohol, fatty acid coated SPIO particles, and umbelliferone (UMB). With placement of the matrices into the release medium, initial UMB release was fast but fell to zero indicating a burst effect. With application of an alternating magnetic field, additional UMB was released. The rate and extent of magnetic field-stimulated release increased with UMB load but not SPIO content. Differences between oleic and myristic acid coated SPIO appeared to be a result of phase separation. UMB release coincided with matrix melting, which can be controlled by the SPIO content and external magnetic field as shown by theoretical analysis. While significant technological issues remain, the foundation for developing magnetic field-stimulated drug delivery systems has been established.