Percutaneous permeability of rhein at shenque acupoint in vitro

To study rhein's permeative properties of acupoint and non-acupoint and different species' transdermal administration in vitro. Cumulative permeation amount and steady-state infiltration rate were taken as evaluative indexes to assess the permeability difference. The Valia-Chien diffusion cell method was used to conduct the permeability test, with fresh acupoint and non-acupoint skin of rat, rabbit and swine in vitro as permeation barriers, and blank 20% EtOH saline as absorption liquid. HPLC was used to determine the rhein. The absorption difference was observed by confocal laser scanning microscopy. The 24-hour cumulative permeation amount through acupoint skin in rats was (102.63±9.60) μg•cm⁻², the steady-state infiltration rate was 4.307 μg•cm⁻²•h⁻¹, both were higher than that through non-acupoint skin. The thickness of acupoint skin in rat was thinner than that in rabbit and swine. The cumulative permeation amount and steady-state infiltration rate of rhein in acupoint of rat were signally higher than those in rabbit and swine. The absorption difference can be clearly observed through an accumulation of fluorescence. In conclusion, species and acupoint all affect the permeability of rhein in vitro. The permeation amount and rate of rhein on Shenque acupoint were better than that on non-acupoint skin, which could verify that treatment through Shenque acupoint is superior to that through non-acupoint. The preliminary mechanism may be the drug delivery through Shenque acupoint as a channel and carrier, which is a visual verification the specificity and superiority of clinical application through Shenque acupoint in treating diseases.