Unraveling the Material Basis of Compound Nanxing Zhitong Plaster: A Multimodal Study Combining Chemical Analysis, Network Pharmacology, and Transdermal Pharmacokinetics

Compound Nanxing Zhitong Plaster (CNZP) is a topical formulation widely used for rheumatoid arthritis (RA), yet its pharmacodynamic material basis is not fully understood. We established a strategy integrating chemical analysis, network pharmacology, and multi-compartment transdermal pharmacokinetics. Comprehensive chemical profiling by UPLC-Q-TOF-MS identified 100 constituents. Network pharmacology screened 15 core bioactive components. A validated UPLC-QqQ-MS/MS method was developed to simultaneously quantify eight components in the stratum corneum (SC) and viable epidermis plus dermis (VD) and four systemically absorbed components in plasma after transdermal administration, elucidating the formulation's in vivo behavior. Pharmacokinetics revealed structure-dependent transdermal patterns: Phenylpropanoids and phthalides showed rapid absorption and elimination, while organic acids, alkaloids, and flavonoids exhibited reservoir effects and slow release in the SC, contributing to a "fast-slow synergistic" mechanism. Given its high transdermal permeability, notable local and systemic exposure, and established anti-inflammatory evidence, ferulic acid is proposed as a potential quality marker for CNZP. This study provides evidence for the in vivo behavior of topical Chinese medicines and suggests methods for quality control and active substance research.