CHAPTER 9: ReGel™ Hydrogels for In Vivo Applications

Thermosensitive drug delivery systems, such as ReGel, are intelligent polymers that take advantage of a physiological, reproducible stimulus to generate a controlled release depot once injected. ReGel copolymers are a family of biodegradable, synthetic copolymers that have demonstrated wide ranging capabilities to deliver hydrophobic small molecules, peptides, and proteins. ReGel copolymer characteristics discussed in this chapter are based on well-defined polymer chemistry, which takes advantage of copolymer constituents studied in a number of polymer-based therapeutics, including polyethylene glycol, D,L-lactide, glycolide, and caprolactone. Various configurations have been prepared and studied and, as a result of the knowledge gained to date, various improvements in controlling the rate and duration of release, biodegradation, broader formulation capability, and improved handling characteristics have been achieved. This chapter outlines various ReGel copolymers developed, their characteristics, and utility by providing specific examples detailing individual ReGel copolymers and controlled release formulations.