Percutaneous Microdialysis and Pharmacokinetic Study of Tongluo-Qutong Rubber Plaster in Rats by UPLC-MS/MS:

Tongluo-Qutong rubber plaster (TQRP) is a well-known traditional Chinese medicine prescription for the treatment of osteoarthritis and cervical spondylosis. Due to a lack of in vivo permeation data, the active ingredients of TQRP have not been fully elucidated, presenting a huge obstacle to quality evaluation, pharmacokinetic studies, and safety assessment of TQRP for clinical application. In this study, a selective and reproducible ultraperformance liquid chromatography tandem mass spectrometry method was developed and validated for percutaneous microdialysis and pharmacokinetic experiments. In the percutaneous microdialysis study, the mean area under the concentration-time curve (AUC(0-24h)) of emodin (EMO) and piperine (PIP) were 127.1 and 2603.6 h.ng/mL, respectively. In the pharmacokinetic study, ferulic acid (FA), EMO, and PIP were determined in plasma samples. The mean AUC(0-32h) values of FA, EMO, and PIP in plasma were 15441.5, 202.0, and 1704.5 h.ng/mL, respectively. The in vivo exposure levels of active ingredients such as FA, EMO, and PIP after dermal administration of TQRP provide insights and data to support identification of its bioactive components and further study of its mechanism of action.