Transdermal drug delivery using disk microneedle rollers in a hairless rat model

Abstract

Transdermal drug delivery systems (TDDSs) represent more reliable and consistent methods of drug dosing than oral administration. However, TDDSs can administer only low molecular weight (MW) drugs and require a power source. Disk microneedle rollers facilitate the passage of low and high MW substances through the direct perforation of the stratum corneum and dermis, without stimulating dermal nerves. We investigated in vitro whether disk microneedle rollers, developed for the Diskneedle Therapy System (DTS™) in South Korea, can deliver drugs effectively through the skin of hairless rats. The disk microneedle rollers used in the DTS™ are metal and consist of several plates bearing microneedles of graded lengths (0.15 mm, 0.25 mm, 0.50 mm). To test in vitro permeation, the skin of a hairless rat was mounted in a Franz diffusion cell system and rolled with a disk roller without microneedles and with rollers fitted with microneedles of each size. Rhodamine B base (80 μl) was applied to the skin for 24 hours, 48 hours, and 72 hours, and dye permeation was detected at 543 nm. Dye binding to the skin was also confirmed using fluorescence microscopy at six hours after the application of rhodamine B. Use of the disk microneedle roller increased the skin penetrance of rhodamine B base in hairless rats in accordance with microneedle length, as assessed using a fluorescence penetration test. Disk microneedle rollers, as designed for the DTS™, can be used for transdermal drug delivery. Microneedles can be selected according to the length appropriate for each application.