Dermal drug delivery: Revisited.

The unique histological and molecular organization of skin poses a formidable barrier to drug delivery into and across skin. Due to the severe restrictions on molecular transport, only potent and lipophilic drug candidates have been able to successfully enter the market. New drug discovery programs based on high-throughput screening and combinatorial chemistry have lead to synthesis of potent but highly lipophilic molecules, and yet these molecules are difficult to deliver by conventional routes of administration. (trans)dermal delivery offers an attractive route of administration for these lipophilic molecules. Further, the diverse opportunities offered by genomics and proteomics cannot be effectively utilized without an equally diverse delivery approach. Skin offers a convenient and effective route for those genes and proteins due to the presence of the stem cell compartment in the epidermis.