Abstract:

Based on the concept of full resource utilization and“the integration of medicinal and adjuvant substances”, the Notopterygii Rhizoma volatile oil microemulsion (NVO-ME) was prepared using the volatile oil, which is the main medicinal part, as the oil phase. The NVO-ME and the after-distillation aqueous extract were then combined to develop a Notopterygii Rhizoma extract microemulsion gel (NE-ME-gel), intended for the treatment of rheumatoid arthritis. The physicochemical properties of NVO-ME and NE-ME-gel were characterized, and the transdermal performance and skin irritancy of NE-ME-gel were investigated. An arthritis rat model was established using complete Freund's adjuvant to evaluate the pharmacodynamic effects of NE-ME-gel. Characterization experiments showed that the NVO-ME had an average particle size of 17.96 ± 0.52 nm, a polydispersity index of 13.2% ± 0.6%, spherical emulsion droplets without adhesion, and Fourier transform infrared spectroscopy results indicated the successful encapsulation of the active ingredients. After preparation into NE-ME-gel, the formulation exhibited weak acidity, moderate viscosity, and transdermal characteristics of low permeability and high retention, with no skin irritation, meeting the requirements for topical drug delivery. In the adjuvant-induced arthritis rat model, NE-ME-gel significantly alleviated paw swelling, improved joint pathological damage, and downregulated serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and anti-cyclic citrullinated peptide (anti-CCP) antibodies (P < 0.001). It also significantly reduced the expression of TNF-α, IL-1β, and IL-6 in synovial tissue (P < 0.001), with no changes in liver and kidney function-related aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine (CRE) levels, demonstrating good safety. In conclusion, the NE-ME-gel developed in this study exhibits well-controlled quality, favorable stability, and a good safety profile. It treats rheumatoid arthritis by suppressing the inflammatory response.

Key words: Notopterygii Rhizoma; extract, microemulsion gel, transdermal drug delivery, rheumatoid arthritis