TranScreen-N: Method for rapid screening of trans-ungual drug delivery enhancers

Topical monotherapy of nail diseases such as onychomycosis and nail psoriasis has been less successful due to poor permeability of the human nail plate to topically administered drugs. Chemical enhancers are utilized to improve the drug delivery across the nail plate. Choosing the most effective chemical enhancers for the given drug and formulation is highly critical in determining the efficacy of topical therapy of nail diseases. Screening the large pool of enhancers using currently followed diffusion cell experiments would be tedious and expensive. The main objective of this study is to develop TranScreen-N, a high throughput method of screening trans-ungual drug permeation enhancers. It is a rapid microwell plate based method which involves two different treatment procedures; the simultaneous exposure treatment and the sequential exposure treatment. In the present study, several chemicals were evaluated by TranScreen-N and by diffusion studies in the Franz diffusion cell (FDC). Good agreement of in vitro drug delivery data with TranScreen-N data provided validity to the screening technique. In TranScreen-N technique, the enhancers can be grouped according to whether they need to be applied before or simultaneously with drugs (or by either procedures) to enhance the drug delivery across the nail plate. TranScreen-N technique can significantly reduce the cost and duration required to screen trans-ungual drug delivery enhancers.