Transdermal drug delivery by coated microneedles: geometry effects on drug concentration in blood

Drug administration through transdermal delivery is restricted by the top layer of skin, the stratum corneum. One possible solution to overcome the barrier function of the stratum corneum is to employ microneedle arrays. However, detailed theoretical models relating drug-coated microneedles and their geometry to the drug concentration in the blood are limited. This article aims to address this issue by examining the blood concentration profiles for a model drug, insulin, that has been administered via coated microneedles. A mathematical model is introduced and applied to predict theoretical blood concentrations. Furthermore, the insulin concentration was a rocket-shaped needle with a constant up angle of 90 degrees. Also, it has been found that the number of microneedles in an array is the most significant factor in determining maximum insulin concentration in the blood (C-h (max)). Penetration depth of the microneedle, centre-to-centre spacing and microneedle thickness had a less significant effect on the maximum insulin concentration concentration in the blood. It is envisaged that the current study will help in designing microneedles of optimum size and shape for transdermal drug delivery (C) 2009 Curtin University of Technology and John Wiley & Sons, Ltd.