Mechanical evaluation of polymer microneedles for transdermal drug delivery: In vitro and in vivo.

In this study, we reported two types of PMNs based on polylactic acid (PLA) and polyvinyl alcohol (PVA), respectively. Parafilm M® film, porcine skin, and rats' models were operated to evaluate the mechanical properties in vitro and in vivo to find optimal parameters for efficient insertion. Insertion depth was measured using Digital Force Gauge by changing insertion force and speed, respectively. Results showed that increasing the insertion force and speed used for PMNs application led to a significant increase in the depth of insertion. A force of 18 N under a speed of 330 mm/min was the optimal condition for inserting PMNs array into Parafilm M® film and porcine skin. In addition, PLA-MNs exhibited higher robustness and enhanced homogeneity in insertion depth compared with PVA-MNs, but PVA-MNs were able to reach much deeper insertion depth. Moreover, Sprague Dawley (SD) rat experiments confirmed the effectiveness of optimal insertion parameters for transdermal drug delivery. This study illustrated not only the development of novel PMNs but also the mechanical evaluation for the design of PMNs. [ABSTRACT FROM AUTHOR]