Cosolvent Effects on the Gel Formation and Gel Melting Transitions of Pluronic® F127 Gels

Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock copolymers, called poloxamers (Pluronics®) are nonionic surfactants that form clear, thermoreversible gels in water. These gels are of pharmaceutical interest because they can be used to modulate drug release based on temperature changes, and are being increasingly exploited for topical, transdermal, ophthalmic, and implantable applications (1-4). Pluronic F127 (F127), which has a nominal molecular weight of 12,500 and a PEO:PPO ratio of 2:1 by weight, is the most widely used of die Pluronics in such pharmaceutical systems.