Agomelatine 3D-printed microneedles as a potential drug delivery system for the treatment of depression

Microneedles (MNs) are small devices that help to overcome the skin barrier and, thus, increase the effectiveness of transdermal drug delivery. This approach could be beneficial, especially for drugs characterised by low oral bioavailability, such as the antidepressant agomelatine (AGM), which is now only available on the market as an oral tablet. The aim of this study was to obtain agomelatine-loaded microneedle systems for potential use in the treatment of depression, using the 3D-printing methods. 3D-printing is an emerging technology enabling the manufacture of drug dosage forms or devices in a personalised, fast, and cost-efficient manner. Three 3D-printing techniques, different drug loading methods, and various shapes of microneedles were investigated along with the mechanical and physicochemical evaluation, release, stability, and toxicity studies of the obtained samples. Masked Stereolithography (MSLA) and PolyJet methods were successful in obtaining good-quality microneedle systems. Additionally, the MSLA method allowed for easy combining of the resin with the drug. The presence of the drug in the product was confirmed, and the drug release pattern depended on the loading method. Mechanical testing showed that Pyramid and Cone geometries were the most promising in puncture tests, and stability testing revealed the need for light- and moisture-resistant packaging. The formulations selected based on the obtained results will be further investigated on the way to create a transdermal alternative to agomelatine oral tablets and increase the effectiveness of depression treatment.