ABSTRACT
The drug delivery market is estimated to be about $80 billion, and one driving factor for its growth is the need for innovative delivery systems for biopharmaceuticals that typically cannot be administered by oral administration. They could be administered by the parenteral route, but repeated injections are often required due to their short half-lives. Noninvasive delivery systems are therefore highly desired. Furthermore, biopharmaceuticals may constitute about 25% of the total pharmaceutical market; therefore, interest in technologies that might enable noninvasive or minimally invasive delivery of biopharmaceuticals is on the rise. Pulmonary administration was one such promising system, but interest has diminished following the withdrawal of inhalable insulin (Exubera®) from the market. Transdermal delivery would be a very attractive route of administration, but most biopharmaceuticals are hydrophilic macromolecules that do not normally enter the skin (1). Physical enhancement techniques discussed in this book, in particular the microporation technologies, can enable the transdermal delivery of these macromolecules, irrespective of their size. These macromolecules include large proteins and vaccines. As discussed in Chapters 3 and 9, microneedles offer signi•cant advantages for vaccine delivery. Therefore, microporation-based technologies may capture a good portion of the drug delivery market and perhaps, more importantly, they may capture some portion of the global vaccine market, which is around $10 billion. They may become an important class of the currently estimated $15 billion worldwide transdermal market. Furthermore, the global dermatologicals market is estimated to be around $18 billion (2), with sales of Duragesic® (fentanyl) patch alone exceeding $1 billion. Over $150 billion worth of brand-name drugs will come off patent in the next 5 years, creating signi•cant opportunities for generic drug delivery systems, including transdermals. The focus of this chapter is on the commercial development of microneedles and iontophoresis,
as these two technologies have perhaps seen the highest activity for commercial development efforts. Commercial development of sonophoresis is limited to a very small number of players and is discussed in Chapter 6. Electroporation is a promising method for delivery of DNA vaccines, and this was discussed in Chapter 5.
