Thermosensitive Hydrogels Based on Combination of Pluronics As New Delivery Systems for Leflunomide

This work is aimed at the preparation and investigation of the properties of thermosensitive hydrogels based on a combination of Pluronics with various architectures for the controlled delivery of leflunomide. In the course of this work, the gelation behavior of Pluronics F127, F68, and L64 was studied. It was shown that the phase transition temperature of F127 solutions increases upon the addition of F68 or L64, enabling optimization of the gelation temperature. Binary hydrogels with the same sol–gel transition temperature (32°С) but varying ratio of Pluronics were obtained. The structural and mechanical properties of the hydrogels were found to correlate with the total weight fraction of Pluronics. Investigation of intermolecular interactions showed a high affinity of leflunomide to F127 and L64 micelles within the polymer matrix of the binary hydrogels. The leflunomide release from the hydrogels was studied in phosphate buffer solution and in biorelevant medium simulating synovial joint fluid.