Formulation and characterisation of dissolving microneedles for the transdermal delivery of therapeutic peptides

The highly effective barrier properties of the stratum corneum (SC) limit the application of transdermal delivery to relatively small, lipophilic molecules. Microneedles (MNs) however, offer a route to effectively deliver a wide range of pharmaceuticals through the skin, bypassing the SC in a non-invasive and pain-free manner. This study presents a dissolving MN system composed of polyvinylpyrrolidone (PVP) and trehalose to encapsulate active pharmaceutical peptides within the MN matrix. Rapid systemic delivery is then achieved once the needles have penetrated the SC and dissolved in the interstitial fluid of the skin. A variety of characterisation techniques were carried out to determine the optimum formulation. A model peptide, polymyxin B, was then incorporated into the MN system and delivered through porcine skin. In addition, the activity of the model drug was monitored during all stages of the formulation process.