Fast-Embeddable Grooved Microneedles by Shear Actuation for Accurate Transdermal Drug Delivery

The study developed a new method for transdermal drug delivery using grooved microneedles (MNs) made from hyaluronic acid (HA). These MNs can be embedded into the skin by mechanical fracture following simple shear actuation, overcoming the limitations of existing MNs that require long-time skin attachment. The amount of triamcinolone acetonide (TCA), a drug used for alopecia areata, delivered can be controlled by adjusting the position of the groove structure and the concentration of TCA loaded in the MN. The MN tip inserted into the skin can be easily broken by shear force, and an easy-to-operate applicator was fabricated to provide adequate shear force, ensuring accurate delivery into the skin with a high probability (98% or more). The study confirmed that TCA in the MN tips was released over a long time, more than 80%, for 72 hours in rat skin. The grooved MNs are expected to increase patient convenience and provide an accurate drug dosage, and can be used for the application of several drugs due to their high-speed drug delivery system and long-term drug release capability.