Preparation and sustained-release mechanism of hydroxybutyl chitosan/graphene oxide temperature-sensitive hypoglycaemic subcutaneous implants.

The current situation of diabetes prevention and control is extremely severe. For instance, glimepiride (GLM), a third-generation sulfonylurea, demonstrates suboptimal clinical efficacy in oral dosage forms, which underscores the pressing need for the development of a new dosage form. Recently, in situ gel subcutaneous implants have garnered considerable attention. Hydroxybutyl chitosan (HBC) can spontaneously crosslink to form a thermosensitive hydrogel and has good biocompatibility. However, its application is hindered by its limited mechanical properties. Graphene oxide (GO), known for its stable dispersion in water, can load GLM through π-π stacking interactions. When combined with HBC, GO enhances the mechanical properties and stability of the hydrogel. Therefore, an HBC-GO@GLM hydrogel was prepared. Rheological analysis revealed that the incorporation of GO increased the critical gelation temperature of the 5 wt% HBC hydrogel from 19.1°C to 27.2°C, considerably enhancing the mechanical properties of the hydrogel. Using encapsulation efficiency as an evaluation index, the optimal encapsulation efficiency of GO@GLM was determined to be 73.53% ± 0.45% with a drug loading capacity of 27.39 ± 0.17% using the Box-Behnken design model. Computer simulation technology validated the interaction between the materials and the drug release mechanism. Pharmacokinetic results showed that compared to the HBC@GLM group, the half-life (t1/2), mean residence time and the area under the curve for the HBC-GO@GLM group were approximately 3 times those of the HBC@GLM group. Subcutaneous implantation of the HBC-GO@GLM hydrogel for drug delivery considerably extended the drug's action time in the body, thereby maintaining blood sugar levels within a normal and stable range for an extended period.