A 3D-printed microneedle array and reservoir for testing transdermal drug delivery

Currently available approaches for delivering pharmaceuticals and biologicals include oral administration, syringe injection, and delivery through a powered pump or patch. Oral administration is a very common approach that is used to deliver approximately 60% of small-molecule drugs, yet it is very difficult to use for the delivery of large-molecule substances due to their poor ability to cross the walls of the gastrointestinal (GI) tract intact. Syringe injection is likely to cause injection site reaction (pain), is inconvenient, and can be problematic because of the non-continuous nature of the delivery. And delivery with a pump, though continuous, requires a battery that is bulky and interferes with daily activity. Therefore, there is a need for transdermal patch drug delivery solutions that use microneedle arrays in order to alleviate the problems outlined above. Our objective for this study is to test transdermal flow characteristics of a custom-built, 3D-printed microneedle array enclosed in a reservoir using porcine skin samples ex vivo. During testing, the 3D-printed apparatus will be connected to the flow channel of a pre-fabricated microfluidic drug delivery device. A number of supracutaneous flow rates will be tested, while flow characteristics including subcutaneous flow rates and hydraulic resistances will be determined. We expect that our apparatus will be able to deliver fluid across the skin continuously and efficiently, and that subcutaneous flow characteristics will not differ significantly from the supracutaneous flow. As an integral component of a patch used for the delivery of drugs such as insulin in humans, the 3D-printed apparatus will be tested for flow characteristics in healthy human subjects and computationally optimized as the next future steps.