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.