Porous microneedle arrays as promising tools for the quantification of drugs in the skin: a proof of concept study

This study aimed to demonstrate the potential of using porous microneedles (PMNs) as a promising tool for the noninvasive quantification of topically applied pharmaceutical products. We fabricated a porous microneedle (PMN) from a blend of cellulose acetate and dimethyl sulfoxide by casting and phase separation; it was characterized using scanning electron microscopy, Raman spectroscopy, differential scanning calorimetry, and a Texture Analyzer. An ex vivo study was conducted as a proof-of-concept study to assess whether this PMN could be used to quantify drug absorption through the skin after the topical administration of two nonequivalent products of sodium ibuprofen (gel and dissolving microneedles). Three cellulose acetate formulations (PMN1: 37.5%, PMN-2: 44.4%, and PMN-3: 50%) were used to prepare PMN patches; subsequently, these were evaluated for their morphological and insertion properties. Only PMN-2 microneedle patches were chosen to continue with the ex vivo study. The ex vivo study results demonstrated that PMNs could absorb and release sodium ibuprofen (SDIB) and differentiate between two different SDIB topical products. This can be attributed to the porous and interconnected architecture of these microneedles. This developmental study highlights the potential success of such a tool for the quantification of dermal drug concentration and supports moving to in vivo tests.