Optimization of a microneedle patch: composition and manufacturing process

Introduction

The effective delivery of active substances through the skin is hindered by the limited permeability of the stratum corneum. Microneedles provide a minimally invasive approach to overcoming this barrier, enabling the transport of bioactive compounds to deeper layers of the epidermis. The aim of this study was to optimize the composition of the polymer matrix and the manufacturing parameters for the production of rapidly dissolving sodium hyaluronate-based microneedles using the freeze-thaw method.

Methods

Sodium hyaluronate solutions were prepared with the addition of inulin or trehalose. The preparation process was optimized by evaluating sonication for air-bubble removal and subsequent shaking of the filled molds. To achieve the desired needle sharpness, three freeze-thaw cycles were performed, varying the duration and method of thawing. The resulting structures were evaluated microscopically, as well as through betanin release assays, agar dissolution tests, and porcine skin penetration tests.

Results

Sonication effectively removed air bubbles from the sodium hyaluronate solutions and improved mold filling. Subsequently, shaking the filled molds for 60 minutes resulted in the best needle formation. Microneedles based on sodium hyaluronate and trehalose dissolved in agar within 30-40 s and penetrated porcine skin to a depth of approximately 350 µm.

Conclusions

The optimized method allowed for the reproducible production of stable patches with well-formed, sharp microneedles, showing rapid release of the model compound and indicating their potential in transdermal therapy.