Fabrication and evaluation of nanoemulsion based insulin loaded microneedles for transdermal drug delivery

<b>Aim:</b> Insulin therapy require self-administration of subcutaneous injection leading to painful and inconvenient drug therapy. The aim is to fabricate nanoemulsion (NE) based insulin loaded microneedles with improved bioavailability and patient compliance. <b>Materials &amp; methods:</b> Different ratios of polyvinyl alcohol and polyvinylpyrrolidone as polymers were prepared through micro-molding technique for microneedles. Characterization of were performed using scanning electron microscope, differential scanning calorimetry, Fourier-transform infrared spectroscopy and circular dichroism. Mechanical strength, hygroscopicity and pain perception of these microneedles were also evaluated. <i>In vitro</i> release, permeation and <i>in vivo</i> PK/PD study of NE-based microneedles were conducted. <b>Results:</b> NE-based microneedles of insulin have improved bioavailability and quick response. <b>Conclusion:</b> Microneedles loaded with insulin can be effectively delivered insulin transdermally to treat diabetes with increased convenience and patient compliance. This study is based on the development of nanoemulsion (NE)-loaded microneedle arrays for transdermal insulin delivery with the objective of effective and painless permeation. NE based insulin loaded microneedles were fabricated using PVA and PVP. Characterization of microneedles using SEM, DSC, FTIR and circular dichroism. Mechanical strength, hygroscopicity and pain perception were evaluated. <i>In vitro</i> permeation using Strat-M membrane and <i>in vitro</i> release studies using rats skin were performed. Comparative <i>in vivo</i> PK/PD studies with standard SC injection and NE were performed showing enhanced insulin bioavailability with rapid hypoglycemic effect.