Synthesis and characterization of thermosensitive hydrogels and the investigation of modified release of ibuprofen

The method of the synthesis of poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate) hydrogels obtained by radical polymerization is described. Their characterization was carried out by the determination of the quantity of residual monomers and by investigating their structure using FTIR. Three glass transitions were detected by DSC method. The porous surfaces of hydrogels with incorporated ibuprofen were shown in SEM micrographs. The swelling ratio of hydrogels decreased with the temperature increase and the swelling transport mechanism changed from non-Fickian to Fickian. Ibuprofen was incorporated in the hydrogel as a drug carrier and the released quantity depending on the temperature was monitored by HPLC. The hydrogel with the lower cross-linker content had the highest swelling degree (alpha = 34.72) at 10 degrees C and released the largest amount of ibuprofen (64.21 mg/g(xerogel)) at 40 degrees C.