Stratum Corneum Permeation and PercutaneousDrug Delivery of Hydrophilic MoleculesEnhanced by Cryopneumatic andPhotopneumatic Technologies

Novel cryopneumatic technology (CPx) and photopneumatic technology (PPx) have been developed to enhance the permeation of the stratum corneum (SC) and percutaneous drug delivery (PDD). CPx produces micro-cracks at the skin surface by successively freezing and stretching the skin with vacuum suction. PPx combines stretching of the skin by vacuum suction with intense pulsed light. The enhancing effects of CPx and PPx were studied on ex vivo porcine skin and in vivo human skin models. Fluorescent hydrophilic macromolecules (FITC and FITC-Dextran) were used as drug surrogates. Fluorescent images of in vivo experiments show that the enhancing effect of CPx is due to drug permeation through the micro-cracks produced by freezing-stretching cycles, while PPx could promote drug permeation through sweat glands. Both ex vivo and in vivo results strongly suggest that CPx and PPx can effectively enhance the permeation of the SC and PDD for the delivery of hydrophilic macromolecules.