(W1130-03-13) Assessing the Impact of Surface Energy of Probe on Adhesive Properties Using Novel 3D Printing Approach

Purpose: The controversial impact of adhesion issues with TDS product are widely debated among pharmaceutical and regulatory scientists, and despite the fact that these issues were first identified several over a decade ago it is only recently that industry and regulatory agency have gained meaningful insights and developed some novel tools to address this hot topic-yielding key insights for other products, as well. Even though, the transdermal patches are evaluated in in vitro studies including adhesion studies, they fail to correlate in in vivo studies. The objective of the present study was to fabricate probes with similar surface energy as human skin using 3 D printing technology and evaluate the adhesive properties of different adhesives used in transdermal patch manufacturing.

Methods: Various silicone adhesives (amine compatible and non-amine compatible) including Liveo BIO-PSA 4501, Liveo BIO-PSA 4202, Liveo BIO-PSA 4502, Liveo BIO-PSA 4602, Liveo BIO-PSA 4102 and Liveo BIO-PSA 4302 were coated on a backing membrane with 5 mg/cm², 10 mg/cm² and 15 mg/cm² dry coat weight. Further all the adhesives were tested for their adhesive properties in probe tack test using texture analyzer (TA-XT plus). All the adhesives were tested using industrial standard TA-57R stainless steel probe, which has surface energy of 500 dyne/cm. The skin has a surface energy in the range of 25-50 dyne/cm depend on the moisture content of it. The polypropylene and polyethylene filament were chosen based on their surface energy which is 32 dyne/cm. Moreover, probes were fabricated using Dremel FDM printer. All the coated adhesives were then evaluated for their adhesive properties using these new probes.

Results: Amine compatible and non-amine compatible silicone adhesives were coated using various backing membrane with the dry coat weight of 5 mg/cm², 10 mg/cm² and 15 mg/cm². Probe tack test results showed significant (p < 0.05) increase in the adhesive force required to unbound the probe from the adhesive on coating 10 mg/cm² dry coat weight as compared to 5 mg/cm² dry coat weight. Additionally, probes printed using Polypropylene and polyethylene filaments showed significantly less (p < 0.001) adhesive force required to unbound the probe from the adhesive as compared to TA-57R Stainless steel probe.

Conclusion: This is the first report of printing novel 3D printed probes using polypropylene and polyethylene filaments to mimic the human skin characteristics. These novel probes can be used for the in vitro in vivo correlation of transdermal products.