Effect of delivery parameters on immunization to ovalbumin following intracutaneous administration by a coated microneedle array patch system.

Immunization to the model antigen ovalbumin was investigated using a novel intracutaneous delivery system consisting of antigen-coated microneedle arrays. The influence of the following parameters on the resulting immune responses was investigated: depth of vaccine delivery, dose of vaccine delivered, density of microneedles on the array, and area of application. The immune response was found to be dose dependent, and mostly independent of depth of delivery, density of microneedles, or area of application. Our studies show that the shortest, most tolerable microneedle arrays can be used for achieving consistent and high antibody titers. Overall, the microneedle array proves to be a very versatile delivery technology, allowing easy and reproducible antigen delivery to skin for efficient vaccination without the use of a needle and syringe.

Transdermal delivery of desmopressin using a coated microneedle array patch system.

Desmopressin is a synthetic peptide hormone chiefly used for treatment of enuresis in young children. It is available in injectable, intranasal, and oral formulations. While administration by injection is poorly suited for routine use in young children, intranasal and oral administration result in low and variable bioavailability. This study therefore explored the feasibility of administering desmopressin transdermally using Macroflux technology, which uses a microneedle array to overcome the skin barrier. The tips of microneedles in 2-cm2 arrays were covered with a solid coating of various amounts of desmopressin and applied to the skin of hairless guinea pigs for 5 or 15 min. Pharmacologically relevant amounts of desmopressin were delivered after 5 min. Bioavailability was as high as 85% and showed acceptable variability (30%). Immunoreactive serum desmopressin reached peak levels after a Tmax of 60 min. Elimination kinetics for serum desmopressin was similar after transdermal and intravenous (IV) delivery, suggesting the absence of a skin depot. Only 10% of the desmopressin dose loaded onto the microneedle array was found on the skin surface after application. Additionally, the patches were well tolerated. These results suggest that transdermal delivery of desmopressin by Macroflux is a safe and efficient alternative to currently available routes of administration.