Nanoparticulate delivery systems for treating multi-drug resistance

An encapsulated delivery system, and, in particular, a nanoparticulate delivery system representing a qualitatively different approach to overcoming multi-drug resistance while simultaneously administering the chosen drug treatment to a patient, e.g., in a site-specific manner, is disclosed. A composition according to the invention includes a therapeutically effective amount of one or more multi-drug resistance reversing agents selected from the group consisting of ceramide and ceramide modulators; and a therapeutically effective amount of a therapeutic agent, wherein the therapeutic agent is different from the one or more multi-drug resistance reversing agents, and the one or more multi-drug resistance reversing agents and the therapeutic agent are encapsulated, preferably co-encapsulated, in a biocompatible, biodegradable delivery vehicle for delivery to a patient in need of treatment, for example, for specific localization at, or higher probability of delivery to, a treatment site in a patient administered the composition. Preferably, the one or more multi-drug resistance reversing agents are ceramide, paclitaxel or tamoxifen.