Novel rotation-based spray-coating method extends release profile of dissolving microneedle arrays

Microneedle arrays (MNAs) offer a minimally invasive route for delivering water-soluble active ingredients like peptides and proteins, bypassing the Stratum corneum with minimal pain and improved patient compliance. While dissolving microneedles (DMNAs) are promising, achieving an extended-release profile remains a significant challenge, often limited by carrier and API compatibility. Current immediate-release DMNAs necessitate frequent application, hindering their utility for therapies requiring sustained drug levels. Developing methods to control drug release from DMNAs is crucial for expanding their therapeutic applications, particularly for chronic conditions or those requiring prolonged systemic exposure. This gap highlights the need for innovative coating techniques to modulate release kinetics.

Researchers developed a novel rotation-based spray-coating method to modify the release profile of dissolving microneedle array (DMNA) cores. The DMNAs contained fluorescein isothiocyanate-labelled bovine serum albumin (FITC-BSA), a model protein, as the active ingredient. For the coating material, the pH-independent methacrylate polymer, Eudragit RS, was utilized. The study employed various analytical techniques including microscopic and Raman mapping experiments to assess coating uniformity. Texture analysis and mechanical penetration studies were conducted to confirm successful skin penetration. Finally, dissolution and ex vivo permeation studies were performed to verify the extended-release profile achieved by the coating layer.

The novel rotation-based spray-coating technique successfully produced uniformly coated dissolving microneedle arrays.

Microscopic and Raman mapping experiments unequivocally demonstrated the coating's uniformity across the DMNA surface, indicating precise control over the application process. Furthermore, texture analysis and mechanical penetration studies confirmed the robust mechanical integrity of the coated DMNAs, verifying their ability to successfully penetrate the skin barrier. Crucially, subsequent dissolution and ex vivo permeation studies provided clear evidence that the applied Eudragit RS coating layer effectively extends the release profile of the model protein FITC-BSA. This modification transformed the immediate-release characteristics of the DMNAs into a sustained-release system, a critical advancement for therapeutic delivery.