Controlled drug delivery products, using biocompatible or biodegradable polymers, have received
considerable attention in the last years. These substances provide in general a more controlled release rate of
assumption of the drug by the body improving its therapeutic action. In fact, there is a growing interest of the
pharmaceutical industry in the development of these systems. Impregnation using supercritical fluid technology has
already proven its feasibility, in the preparation of controlled release systems. In this technique the drug component
is dissolved in a compressed gas (carbon dioxide) that is used as a mobile phase and that, also, swells and stretches
the polymer matrix, facilitating the diffusion of the drug, and increasing the rate of impregnation. A high purity
product, free of residual solvents is obtained, since no organic solvents are involved in the impregnation process. In
this chapter, the development of different successful controlled release systems is presented.