Transdermal delivery of human IgG as a model of macromolecule by physical enhancement techniques

The passive skin permeability to high molecular weight proteins is essentially zero. The enhancement of skin permeation by physical enhancement techniques using human immunoglobulin G (hIgG) as a model drug was investigated. hIgG was used initially to study the feasibility of in vitro permeation under the influence of microneedles (MN), ultrasound (US), and iontophoresis (ITP). For in vitro permeation studies, various parameters such as microneedle length, number of microneedles and donor concentration were examined. Microchannels created by maltose microneedles in hairless rat skin were visualized using methylene blue staining. Cryostat sections were prepared and stained to measure the depth of penetration. Pathways taken by hIgG transported across the skin were visualized by immunohistochemical (IHC) studies. In vivo evaluation was done with human IgG in hairless rats using liquid reservoir patch applied to microporated skin area. The in vitro and in vivo delivery profiles of maltose microneedles and Dermaroller(TM) were compared. Blood samples were collected at predetermined time points and analyzed. Transepidermal water loss (TEWL) and methylene blue techniques were used to determine the open duration of microchannels. The uniformity of pores on rat skin was characterized by processing PPI values in Fluoropore software. Basic pharmacokinetic parameters of hIgG in rats were calculated after intravenous administration of this compound.;The specific penetration of microspheres into hair follicles was qualitatively characterized. The results suggest that spray dried microspheres with size less than 10 micron penetrated into the hair follicles of hairless rat skin when cathodal iontophoresis was applied.;The characterization and development of human IgG formulation using hanging-drop, dynamic light scattering, size exclusion chromatography and differential scanning calorimetry was conducted.;In conclusion, maltose microneedles efficiently enhance transdermal delivery of human IgG in hairless rats both in vitro and in vivo. The tested microspheres successfully penetrated into hair follicles of hairless rat skin. Hanging drop technique is an easy and efficient method to initially screen protein formulation.