Polymeric microneedles for transdermal drug delivery- a review of recent studies

Abstract

Transdermal drug delivery is contemplated as one of the top appealing routes for pharmaceutically active ingredients administration owing to the several benefits, specifically over oral and intravenous routes. Unfortunately, factors such as the active agent's molecular weight and hydrophilicity preclude it from being widely used, especially for macromolecular agents of interest such as DNA, peptides, and siRNA coupled with the excellent outermost skin barrier provided by the stratum corneum. Since the last decade, microneedles (MNs) have gained prominence due to their numerous advantages in transdermal drug delivery. MNs are micron-sized needles that can penetrate the subcutaneous skin layer into the epidermal layer without causing pain by evading nerve fibers and capillaries, primarily found in the dermal layer. Because of their efficiency, painlessness, reliability, and feasibility, they are commonly utilized in TDD systems (TDDS). Different varieties of microneedles, such as biodegradable, dissolvable, hollow, and coated can be fabricated using various materials based on the delivery mechanism. In this review, we first elucidated the anatomy of human skin and thereafter highlighted the development and current status of microneedle technology, mechanism of action on the skin, different types of microneedles, and their advances in the delivery of both low molecular weight molecules and biomacromolecules such as proteins and peptides, including their prospective applications in ocular diseases and chemotherapeutic drug delivery. Microneedle technology holds a lot of potential because of the diverse array of materials it can use, as well as the ease with which it can be made for promising therapeutic applications.