Biodegradable injectable in situ depot-forming drug delivery systems

The scope of drug-delivery systems has expanded significantly in recent years providing new ways to deliver life saving therapeutics to patients. The development of new injectable drug-delivery systems has provided new vistas and opened up unexplored horizons in the field of science, particularly in controlled drug delivery since these systems possess unique advantages over traditional ones, which include ease of application, and localized and prolonged drug delivery. In the past few years, an increasing number of such systems has been reported in the literature for various biomedical applications, including drug delivery, cell encapsulation, and tissue repair. These are injectable fluids that can be introduced into the body in a minimally invasive manner prior to solidifying or gelling within the desired site. For this purpose both natural (chitosan, alginates) as well as synthetic polymers (PEGylated polyesters, ricinoleic acid-based polymers) have been utilized. These systems have been explored widely for the delivery of various therapeutic agents ranging for anti-neoplastic agents like paclitaxel to proteins and peptides such as insulin, almost covering every segment of the pharmaceutical field. This manuscript focuses on the recent advancements in the area of in situ forming biodegradable polymeric drug-delivery systems.