3D-Printed Skin-Mimetic Substrates and Solid-State NMR Improves Patch Adhesion Evaluation

Transdermal rotigotine patches for Parkinson’s disease often face adhesion issues due to skin conditions like micro-delaminations, wrinkles, and roughness. Poor adhesion can cause patches to peel off, leading to inadequate drug delivery and side effects. This study aims to develop rotigotine patches and assess their adhesion properties using innovative 3D-printed skin-mimetic substrates (acrylonitrile butadiene styrene, ABS) that replicate skin conditions during tack and peel adhesion (90° and 180°) testing. Results showed significantly lower adhesive forces on ABS than on stainless-steel substrates, indicating an overestimation by conventional methods. ABS substrates with micro-delaminations and wrinkles further decreased adhesion. Moisture uptake studies using solid-state NMR and FTIR confirmed that moisture can accumulate in the patch and affect adhesion, suggesting the need for moisture-protective agents in formulations. This is the first study to use skin-mimetic ABS substrates for adhesion testing, emphasizing the need for bio-relevant testing methods and moisture-protective agents in transdermal rotigotine patches.