Microneedles for Transdermal Drug Delivery

Abstract

Transdermal drug delivery includes application of drug(s) to the skin for systemic effects. However, relatively few drugs possess the requisite characteristics to passively traverse the skin's stratum corneum barrier. Microneedle (MN) technology is a novel drug delivery technology that increases skin permeability by creating microscopic pores within the skin through which the passive drug diffusion to the dermal microcirculation occurs. This overcomes the barrier to efficient drug permeation. MNs, with different strategies, have shown the ability to enhance transdermal delivery of drugs and biomolecules with different physicochemical properties in vitro, ex vivo, and in vivo. Progressing toward large-scale manufacture, commercialization, and, ultimately, patient use of a MN product, there are several priorities that must be addressed. Evaluation of end user opinion and expectations of a final MN product is an essential step to ensure appropriate MN-patch design. This must be coincided with meeting regulatory requirements in terms of product safety and efficacy. Moreover, suitable manufacturing methods that can be translated to large-scale production are now urgently needed to advance the technology from small-scale laboratory fabrication to commercial scale. Evidence of MN technology efficacy has been widely demonstrated, particularly in different animal models and several small clinical trials. As the necessary manufacturing advancements are made, extensive clinical trials need to be conducted. It is expected that the first MN products will be based on the delivery of vaccines and small, hydrophilic drug compounds or a MN diagnostic device as, to date, these have been most extensively studied.