Objective: To investigate the effect of stimulating the acupoints Feishu (BL 13) and Dazhui (GV 14) on the transdermal uptake of sinapine thiocyanate contained in a gel used for the management of asthma.
Methods: Thirty Sprague-Dawley rats were randomly divided into three equal groups using a random number table: the Feishu (BL 13) acupoint group, the Dazhui (GV 14) acupoint group, and the nonacupoint group or control group. Using microdialysis technology, preprocessed skin probes were implanted into the rats at Feishu (BL 13), Dazhui (GV 14), and a nonacupoint site. Asthma gel was then placed on the skin at Feishu (BL 13), Dazhui (GV 14) acupoints, and the nonacupoint for all groups. Dialysate was collected every 30 min for 12 h. The normalized concentration of sinapine thiocyanate in the skin was determined by high-performance liquid chromatography.
Results: The rat in vivo transdermal experiment demonstrated that the quantity-time equation showed a good linear correlation with zero-order kinetics (r > 0.99). The transdermal behavior was in accordance with the first-order rate open model in which the transdermal penetration rates and the accumulative amounts of sinapine thiocyanate in the skin at the acupoint sites were greater than those through the skin of the nonacupoint site. The systemic maximum concentration and the area under the curve of sinapine thiocyanate in the acupoint groups were significantly greater than in the nonacupoint group. A lag time was observed in both acupoint groups, but not in the nonacupoint group.
Conclusion: Stimulating the acupoints promotes the percutaneous absorption of sinapine thiocyanate and also controls its release, reducing concentration fluctuations in the blood.
Keywords: Acupuncture; Asthma; Microdialysis; Pharmacokinetics; Point BL13 (Feishu); Point GV14 (Dazhui); Skin absorption.