Effect of humidity on mechanical properties of dissolving microneedles for transdermal drug delivery

Dissolving microneedles (DMNs) prepared from soluble polymers has been being widely investigated as a safe and effective transdermal delivery system for drug and vaccine. Limited by the materials, the air humidity would probably affect the mechanical property of DMNs, which is essential for the effective needle insertions and drug delivery. In this study, four kinds DMNs prepared by polyvinyl alcohol, sodium hyaluronate (HA), chitosan and gelatin are studied on the mechanical strength and insertion ability under varying humidity conditions. Based on these investigations, we hope to provide the effective time of DMNs to ensure a successful insertion and drug delivery.