Cubic Liquid Crystalline Gels Based on Glycerol Monooleate for Intra-articular Injection

In situ gels containing sinomenine hydrochloride (SMH) for intra-articular (IA) administration to treat rheumatoid arthritis (RA) were designed and investigated in this study. Glycerol monooleate (GMO) was used due to the potential to generate viscous crystalline phase structures upon water absorption. The gels were evaluated using different parameters: syringeability, gelation, viscosity, and drug release. And, polarized light microscopy (PLM), small-angle X-ray scattering investigation (SAXS), and rheological studies were used to analyze their internal structures. In vitro drug release studies were performed by the dialysis membrane diffusion method. The syringeability, viscosity, gelation time, and water for gelation of the obtained preparation met the requirements of IA injection. PLM, SAXS, and rheological analysis showed that all samples had transformed from flowable isotropic solution phases to the inverse cubic (V₂) phases upon excess water. And, the gels were found to be able to maintain the drug release for more than 1 week. Results showed that in situ gels based on GMO liquid crystalline could provide a sustained system for SMH. Due to its sustained release, the in situ cubic gels were suitable for IA injection to treat RA.