Double layer and dual drug loaded microneedle patch for comprehensive skin therapy
** Lecture will be given in English**
Abstract:
Microneedle based drug delivery provides a minimally invasive strategy for localized and controlled transdermal administration of therapeutics, yet precise temporal control of multi drug release remains challenging in settings that demand both rapid and sustained pharmacological effects. This study presents two microneedle platforms for controlled co delivery of bupivacaine (local anesthetic) and ampicillin (antibiotic), exploiting the distinct dissolution behaviors of hyaluronic acid and chitosan to program release kinetics. In the first design, a double layered microneedle was fabricated with hyaluronic acid-ampicillin confined to the needle tips for rapid dissolution, and a chitosan–bupivacaine core and base to enable slower, sustained release. In the second design, chitosan–bupivacaine microneedles were coated with an outer hyaluronic acid–ampicillin layer to create a fast releasing shell around a sustained release interior. Both microneedle arrays showed uniform morphology and sufficient mechanical strength for skin insertion. Spinning disk confocal microscopy confirmed discrete spatial localization of the polymers in both systems: hyaluronic acid restricted to the tips in the double layered microneedle and forming a distinct outer shell in the coated microneedle, while chitosan remained within the underlying needle matrix. In vitro release studies using Franz diffusion cells demonstrated rapid ampicillin liberation compared with a prolonged bupivacaine release profile, consistent with the designed dissolution hierarchy of hyaluronic acid and chitosan. These findings verify that dual drug delivery with differential temporal profiles can be achieved by integrating polymer specific dissolution kinetics with microneedle architecture. Such platforms may be particularly valuable for clinical applications requiring immediate release such as antimicrobial protection combined with a more extended release such as the case for analgesia, for example, in post surgical care and wound management.
