Advanced Compounding: Compounding with Microneedle Arrays, Part 3: Microneedle Array Development in the Literature...

Microneedle arrays, or microneedle array patches (terms are often used interchangeably), are promising devices for the transdermal delivery of drugs and vaccines. Unique microneedle arrays can be prepared from various materials and can be either solid or hollow. Upon insertion, they rapidly take up skin interstitial fluid to form continuous, open conduits from the attached patch-type drug reservoirs to the dermal microcirculation. Microneedle array patches can be prepared using molds in a wide range of patch sizes and microneedle geometries, can be easily sterilized, resist hole closure while in place, and are removed completely intact from the skin. Delivery of macromolecules is no longer limited to what can be loaded into the microneedles themselves, as they can also be loaded as a reservoir and delivered through the microneedles. Also, transdermal drug delivery can now be controlled by the cross-linked density of the hydrogel matrix rather than the stratum corneum. This newer technology has the potential to overcome limitations of conventional microneedle designs and to greatly increase the range of the type of drug that is deliverable transdermally, which benefits industry, healthcare providers, and, ultimately, patients.