Study Of Transdermal Drug Delivery System Of α-asarone

α-asarone is one of the main component parts in Acorus graninues Soland. It is widely used in asthma, pneumonia and epilepsy, α-asarone is a white crystalline powder with its molecular weight 208. It is insoluble in water, its dosage is 180mg/d. Now in the market there are many products, as tablet, capsule and injection, but the oral products have low bioavailability. The transdermal drug delivery system can increase the bioavailability and reduce the administration times.The purpose of this paper is to investigate the percutaneous absorption characteristics and aim to develop a transdermal drug delivery system. The main three parts of the present study are: the preformulation study involving screening the proper enhancers for transdermal aborption of α-asarone;Formulation study and developing a drug-in-adhesive transdermal patch of α-asarone using Eudragit E100 as pressure sensive adhesives(PSA);The α-asarone reservoir patch was prepared using 1 %HPMC of ethanol solution as medium and EVA membrane for controling the release of drug, and do the research its bioavailability.In the preformulation study, the ultraviolet spectrum and HPLC methods for the assay of α-asarone were established firstly and then the physicochemical properties, especially the octanol/water partition coefficient and the solubility in various solvent systems such as alcohol, PEG 400, IPM, octanol were examined. The prediction permeability was then compared with actual transdermal parameters obtained from the in-vitro diffusion study , and feasibility of drug transdermal absorption was then analyzed. The result indicated that α-asarone was easy soluble in alcohol, carbinol, octanol, Ethyl acetate and, and was a proper candidate for transdermal delivery with its log Ko/w value at 2.86±0.02. Ethanol, IPM Propylene glycol, Azone, and OA were good permeation enhancers, which facilitated the permeation of α-asarone. Combined with enhancers can promote the permeability.The drug-in-adhesive transdermal patch of α-asarone was developed using EudragitElOO as PSA matrix.The foumulation factors such as the effects of different plasticizers and penetration enhacers on the physical quality of patches were investigated through adhesive performance tests. The obtained results indicated that Eudragit ElOO possessed good compatibility with several other excipients examined in this study. The facts that the physical quality of the patches was significantly affected by addition of penetration enhancers suggested the glycerol, oleic acid or IPM did not serve as a simple penetration enhancer, but acted as an additive by molecularly dipersing in the PSA matrix. The in-vitro transdermal performance of the different formulations as well as other evaluation indexes such as drug content, release profiles were also studied.The adhesive performance, release profiles, in-vitro transdermal performance, pharmacokinetics of α-asarone reservoir patches were studied. The reservoir patch was prepared using 1 %HPMC of ethanol solution as medium and EVA membrane for controling the release of drug. The Franz diffusion cells were used and several penetration enhancers were evaluated. HPLC was used to determine a-asarone's content and permeation rate. The drug concentration in plasma was assayed by HPLC, the patches'bioavailability was also studied. The reservoir patch was not irritative. Data showed that the best permeation rate reached 20.67 ± 1.33 μg?cm"2?h"1.