Optimization of dip-coating methods for the fabrication of coated microneedles for drug delivery

Abstract

As an approach of transdermal drug delivery, coated microneedles (MNs) have received extensive attention. Dip-coating method is a commonly used method in the preparation of coated MNs, due to its simple fabrication process and low cost. In this work, we proposed four different coating methods based on the dip-coating process, including dip-coating with a dam board, a roller, a fixture and a limit. The drug loading of the single MN prepared from the four methods was not significant (p > 0.05), from 15 to 16 ng. The minimum deviation of drug loading achieved 12.3% from the fixture device method. The in vitro drug delivery was also evaluated and the results revealed that the MNs fabricated from all methods could achieve about 90% drug delivery efficiency. All the results demonstrated that the dip-coating with a fixture method could guarantee a better homogeneous drug loading, which may be potential for future large-scale production of drug coated MNs.