Author(s): Rachel Beth Groves
The transdermal delivery of therapeutics is limited to only a few molecules due to the outermost layer of skin, the stratum corneum, which acts as a barrier against the ingress of substances into the body. Microneedle arrays, which are commonly between 70µm and 900µm in length, have been developed as a method of promoting drug and vaccine delivery by creating microperforations in the stratum corneum to increase transport into the skin. The design of microneedle devices has significantly developed over recent years to allow for the delivery of numerous compounds into in vivo and ex vivo skin. Microneedle devices are now beginning to be taken away from the laboratory and towards clinical use but to achieve this it is desirable that all microneedles within the device penetrate skin in vivo to a sufficient depth. As microneedle devices have been extensively tested in cadaver tissue, a greater understanding of the mechanical properties of skin in vivo and ex vivo is required and to hypothesise whether animal models such as murine skin ex vivo serves as an appropriate model for human skin ex vivo.