Evaluating adhesion properties of transdermal adhesives using novel skin mimetic substrate

Abstract

Even though, the transdermal patches are evaluated for adhesion testing using current adhesion protocols (based on stainless steel (SS) probe), they fail to correlate to in vivo studies. Therefore, our objective was to print the probes (skin mimetic substrate) using 3D Fused Deposition Modeling (FDM) printing using materials with similar surface energy as skin and evaluate the adhesion property of pressure sensitive adhesives (PSAs). Additionally, the objective of the present study was to study the effect of various intrinsic factors including coat weight, elastic properties of backing membranes and viscosity of PSAs on adhesion properties of PSAs. Our novel 3D printed polypropylene (PP) probe was successfully printed and postprocessed using FDM printing coupled with automated robotic arm setup for adhesion testing. Probe tack test results showed no significant difference in peak adhesive force in case of skin adhered to SS probe and PP probe. However, PP probe showed about 10.26-fold decrease (p<0.0001) in the adhesive force as compared to SS probe. Effect of coat weight using PP robe results revealed that both amine (PSA-4302) and non-amine (PSA-4501) compatible silicone PSAs showed significant (p<0.05) increase in their adhesion prosperities at 10 mg/cm2 as compared to 5 mg/cm2 coating. Further, choice of backing membrane and viscosity of silicone PSAs also showed significant (p<0.0001) effect on PSAs adhesion property. In conclusion, PP probe could be a promising approach for in vitro adhesion testing of TDS products. Further, intrinsic properties including coat weight and viscosity of silicone PSAs significantly affected their adhesion properties.