Hydrogel-Forming Microneedle Arrays for Sustained and Controlled Ocular Drug Delivery

Abstract

Microneedles (MNs) provide a minimally invasive alternative to intravitreal injections and a promising means to sustainable ocular drug delivery. To optimize the sustained drug release profile and to ease the administration of the MN array to the eye, the number of MNs in an MN array and their layout need to be carefully selected. In this study, the drug release kinetics of MN arrays with varying numbers of MNs (8, 12, and 16) is studied over a four-week period. The MN arrays show a much more uniform drug release profile than the single injections. Only the 16-needle MN array fully released all the amount of loaded drug at the end of the 4-week period. Both 8- and 12-needle arrays showed a steady release rate over the 4-week period, which is the longest sustained release duration that has been reported. Zero-order models are created to predict drug release profiles for the three MN arrays. It is estimated that the MN array with 8 needles can deliver the drug for up to 6 weeks. The models can be used to design MN arrays with a given targeted therapeutic index for sustained drug delivery.