Synthesis Of Polarity-modulated Hot Melt Pressure Sensitive Adhesives For Transdermal Drug Delivery

Transdermal drug delivery systems (TDDS) are well-known that they can deliver drugs into the blood circulation system through the skin at constant release velocity for diseases cure. TDDS can avoid first pass effect to the human gastrointestinal tract and liver and are treated to be a new kind of non-invasive drug administrations. Transdermal drug delivery systems of Chinese medicine are generated by combining traditional Chinese medicine theory and the acupuncture theory with modern TDDS theory.With the development of transdermal drug delivery systems of Chinese medicine, the matrix of patch is highly demanded. Due to the excellent drug release property and adhesive peformance of SIS-based hot melt pressure sensitive adhesives (SIS-based HMPSAs), they are widely used as the matrix. But they are only suitable to deliver lipophilic drugs in the TDDS due to their hydrophobic performance. Because the traditional Chinese medicines mostly consist of the lipophilic and hydrophilic components, SIS-based HMPSAs are necesarry to increase the polarity to prepare a novel kind of HMPSAs suitable for hydrophilic drugs. In this work, the epoxidation method was used to increase the polarity of thermoplastic elastomer SIS, which was the skeleton material of HMPSAs for TDDS.Three aspects were studied in the work:(1) the relationship between the epoxidation degrees of ESIS and the reaction conditions, such as reaction temperature, the amount of H2O2, the reaction time. When the reaction temperature and [H2O2]/[C=C] were0℃and1, respectively, the epoxidation degrees of ESIS were linear with reaction time.(2) The micro-structures of SIS and ESIS were studied by the atomic force microscope (AFM), the contact angle, DSC. The ESIS polarity was continuously improved with their epoxidation degrees. The phase structures of ESIS and the ESIS/C5compatibility were changed, which greatly affected the performance of HMPSAs. When ESIS was used as the skeleton of HMPSAs, the hydrophilic and lipophilic drugs release performance and the adhesive pefoemance were investigated.(3) For H-ESIS based HMPSAs, the drug release properties increase with the improvement of ESIS polarity due to the formation of bicontinuous phases, and the adhesion performance was firstly increased and then decreased with sacrifice of SIS flexibility and ESIS/C5compatility due to the introduction of polar function groups.(4) For H-SIS/RLPO based HMPSAs, the introduction of ESIS improved the hydrophililc drug release and adhesion performances including180℃pelling strength and holding power.