Improving the Hydrophilic Properties of Deproteinized Natural Rubber Latex Films for Lidocaine Transdermal Patches by Starch Blending

This research developed lidocaine transdermal patches which were composed of deproteinized natural rubber latex (DNRL), several types of gelatinized starch, and glycerin. The characteristic evaluation, in vitro drug release and permeation, and product stability were performed. The hydrophilic properties, i.e., swelling ratio, volumetric porosity, erosion, and moisture uptake of blended films were increased by adding starch. The gelatinization of starch should be formed for constructing a well combined film. An increasing amount of starch could enhance the swelling ratio and erosion values. The ultimate tensile strength and elongation at break of DNRL-starch blended films at the lowest starch amount of 5 phr of rubber were similar to the pure DNRL film. Mechanical properties tended to rise up when mixed DNRL with a higher amount of starch. Either gelatinized mung bean or corn starch could be constructed for lidocaine-loaded blended films with good appearance and acceptable characteristics. These films could release the drug up to 80% at 12 h, and lidocaine could permeate from DNRL-starch blended films through the skin better than DNRL matrix film itself. At 4 °C of storage temperature, it was the most suitable condition for film storage in this study.