Microneedles for Transdermal Drug Delivery: A Systematic Review

Abstract

Transdermal delivery has the benefit of bypassing the first-pass effect and allowing for long-term drug release. The stratum corneum (SC), on the other hand, creates a barrier, which limits drug delivery. Microneedles are a painless, less invasive, and easy-to-use transdermal drug delivery system that has a high drug bioavailability. The transdermal method has been investigated for a variety of drugs because of its advantages of bypassing the first-pass effect and allowing for long-term drug release. The distribution of numerous medicinal substances across the skin has become difficult due to the skin’s strong barrier qualities, particularly the stratum corneum, only a few medications with appropriate physicochemical qualities (molecular weight 500 Da, enough lipophilicity, and low melting point) can be delivered efficiently through the skin. Hydrophilic medicines and macromolecular agents such as peptides, DNA, and small interfering RNA, on the other hand, are difficult to transport. Drug penetration into the SC can be accomplished by bypassing or reversibly disrupting the SC layer using a variety of methods. The use of micron-scale needles in improving skin permeability has recently been proposed and proved to greatly increase permeation, especially for macromolecules. Microneedles (MNs) can pass through the skin’s SC layer and into the live epidermis, avoiding nerve fibers and blood vessels, which are mostly found in the dermal layer. Hypodermic needles, topical creams, and transdermal patches are the most common methods for transdermal drug administration. Microneedles are a novel type of delivery method that helps to improve medication administration through this route while also solving the issues that come with traditional formulations. The fundamental mechanism entails disrupting the skin layer, resulting in micron-sized channels that lead the medication directly to the epidermis or upper dermis region, where it can bypass the barrier and enter the systemic circulation.