Abstract: The present invention provides high-concentration formulations of opioids such as fentanyl or fentanyl congeners. The formulation of the invention comprises fentanyl or a fentanyl congener in concentrations significantly in excess of conventional formulations, e.g., on the order about 2-fold to about 10,000-fold greater than conventional formulations, e.g., currently commercially available formulations. These formulations are particularly useful for long-term delivery to a subject suffering from pain. The invention further provides drug delivery devices comprising the high-concentration opioid formulations, and further provides methods of alleviating pain in a subject, comprising administering the high-concentration formulations to a subject in need thereof.

Abstract: The present invention provides a catheter for use in delivering formulation that allows modification of the formulation prior to or concomitant with its transport or at a delivery site. The catheter comprises an elongate body, which defines an inner lumen extending between the proximal and distal ends, and a modifying element, which provides for modification of one or more components of a formulation prior to or concomitant with release at the delivery site.