Breaking the Skin Barrier: Modelling Microneedles for Transdermal Insulin Delivery

Transdermal patches, devices developed to deliver drugs, can be limited in their efficacy because the amount of drug that diffuses through the skin often doesn’t reach sufficient concentrations. This problem is alleviated by using the ‘poke with patch’ method, which uses a patch with microneedles to puncture the skin in order to help increase drug penetration through the skin. In our project, we investigated varying number of punctures and modeled how that impacts drug diffusion through the skin over time. We modeled this system in COMSOL as a 2D slab representing the multiple layers within the skin, and simulated insulin flow from the patch into the capillary blood layer. To study the effect of the number of punctures on drug delivery, we created four models with 5, 10, 20, and 50 microneedle punctures. We then gathered data of insulin concentrations over 24 hours at two different points in the geometry—underneath a microneedle and at the exit of the blood domain—as well as in the drug patch and in the body. The data gathered from all four models were then evaluated to find the trends. The data collected showed that as we increase the number of microneedles in the patch, the insulin concentration underneath the needle decreases. However, with a greater number of microneedles, the insulin concentration exiting the blood domain significantly increases, and insulin exits the drug patch at a faster rate. From our results, we see that the addition of microneedle punctures improves the efficacy of transdermal patches by increasing the insulin delivered into the body through the patch. Since insulin concentration in the blood increases when there are more microneedles in the patch, we can conclude that increasing the number of microneedle punctures optimizes drug delivery. However, there should be a limit on the number of punctures to prevent potential clinical damage to the skin