In Vivo Study on Site of Action of Sinapine Thiocyanate following Acupoint Herbal Patching

Objective. To investigate the site of action of sinapine thiocyanate (ST), following acupoint herbal patching (AHP). Methods. Twenty Wistar rats were randomized into five groups (groups A, B, C, D, and E), and all groups received the same AHP in vivo. Skin samples were excised at 2 h, 4 h, 6 h, 10 h, and 26 h after AHP administration from group A to group E separately and the concentrations of ST in the skin were determined using a liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method. A pharmacokinetic profile of ST following AHP was performed at the same time in a group of five Wistar rats to detect plasma levels at the same time intervals. Results. The mean +/- SD ST concentrations (ng/ml) at 2 h (group A), 4 h (group B), 6 h (group C), 10 h (group D), and 26 h (group E) after AHP administration were 250.01 +/- 61.99, 61.01 +/- 30.41, 40.12 +/- 26.94, 78.66 +/- 59.43, and 19.55 +/- 18.95, respectively. No ST was detected in rats' plasma samples at the same time points. Conclusions. The site of action of ST following AHP is in the skin.