ABSTRACT
The skin as a delivery route has many potential benefits among which avoidance of first pass metabollsm, quasi first order kinetics and improved patient compliance are probably most important. This therapeutic and commercial potential with an annual turnover approaching two billion US dollars world wide, has attracted a substantial amount of research effort from academics and the pharmaceutical industry over the last two decades. The majority of TTS (through the skin) delivery systems currently on the market are based on variations of the established patch technology. This technology is, however, limited to the delivery of a minority of drugs such as highly active small molecular weight (<500 Dalton) compounds. Techniques that often involve complex devices ranging from particle guns and iontophoretic devices to electroporation have been employed to overcome these limitations. The non-invasive delivery of topically applied molecules larger than 500 Dalton remains a challenge to date, however.
