A Hollow Microneedle Carrier for Enhancing Skin Penetration of Large Molecular Compounds

Abstract

Delivery of drugs through skin is obstructed by the excellent barrier properties of the outermost skin layer, the stratum corneum (SC). A strategy employing microneedles have recently emerged as a minimally invasive device for disrupting the SC structure and creating holes for molecules to pass through. Hollow-typed microneedles permit drug delivery which can be modulated over time via active delivery controlled by hand or pump. In this study, the potential of hollow microneedle for overcoming the outermost skin barrier and facilitating drug delivery into skin was investigated. Fluorescein isothiocyanate (FITC)-dextrans (4.3 kDa), FD-4, was used as a model large molecular compound. The effects of injection volume and formulation on drug release behavior from skin were determined. FD-4 was favorably loaded into the lower epidermis as well as the superficial dermis of the skin by a hollow microneedle. The release profiles of FD-4 were analyzed by Higuchi model based on Fick’s law of diffusion. The higher the volume of FD-4 solution injected, the faster the FD-4 release rate from skin. Liposome formulation exhibited no difference on drug release profiles compared with the solution. The results provide information for designing an effective hollow microneedles system.