Over the last twenty-five years, more than thirty-five transdermal patch products have been introduced to the market; however, because of physical limitations such as molecular size, these passive diffusion products encompass a narrow range of applications. Currently, the market for transdermal drug products is largely restricted to pain management, hormone replacement therapy, and cardiovascular therapy, with sales being derived from just about twelve drugs.

The market for transdermals is likely to expand dramatically when macromolecules such as proteins, peptides and vaccines, can be delivered through the skin. There are a number of second generation patches under development which employ active delivery, in which the stratum corneum is breached to enhance the permeability of the skin. This includes the use of electrical, mechanical, electronic and ultrasound forces to promote drug absorption. The market should be receptive to these newer technologies, as the transdermal dosage form has been embraced by both physicians and patients because it is user-friendly, convenient and painless while offering multi-day dosing and generally improved compliance. The worldwide sales for transdermal products were nearly $13 billion in 2005 and are projected to grow at double digit rates through 2010. When compared with the total worldwide prescription drug sales of $550 billion, transdermal products account for less than 2.5 percent of the market.