Transdermal Delivery of Rhizoma Coptidis and Evodia Rutaecarpa: The Effects of Enhancers on Permeation Across SD Mouse Skin

Abstract Background: Oral ulceration is a common, painful condition of uncertain aetiology. Traditional Chinese medicine has good effect. One kind of treatment method is to use rhizoma coptidis, evodia rutaecarpa powder 10g each mixed with vinegar to paste in the foot springs point. The purpose of this study is to convert this prescription into a corresponding preparation for everyone's convenience. Methods: The enhancement effect of a series of different concentrations of fat-soluble azone, water-soluble azone, dimethyl sulfoxides, acetic acid, on the skin permeability of rhizoma coptidis, evodia rutaecarpa powder was studied in vitro by using Franz diffusion cells and SD mouse skin. The concentrations of the main components palmatine hydrochloride, berberine hydrochloride, evodiamine, rutacarpine in the preparation were determined by an HPLC method. Results: The addition of dimethyl sulfoxide, 2-8% w/w water-soluble azone, 8% w/w fat-soluble azone never increased palmatine hydrochloride and berberine hydrochloride flux with respect to the control preparation. The enhancing effects of 45% acetic acid, 1% water-soluble azone and 5% fat-soluble azone were evident on the palmatine hydrochloride and berberine hydrochloride permeability. The target substances evodiamine and rutacarpine were not detected in the receiving solution, and there were residues in the skin, respectively. The amount of evodiamine and rutacarpine residued in the skin obtained from formulations including 45% w/w acetic acid or 5% w/w fat-soluble azone were significantly higher (p<0.05) than that obtained from the blank control formulation. Conclusions: The experimental results revealed that 5% fat-soluble azone transdermal agent has the optimal performance in the rhizoma coptidis, evodia rutaecarpa preparation.