Transdermal drug delivery.

Transdermal drug delivery is a validated technology contributing significantly to global pharmaceutical care. Since 1980, impressive growth in this field has been observed with many commercial successes; importantly, a new chemical entity was recently developed and approved for transdermal administration without having first been given as an injectable or oral dosage form. The progress achieved has been based on the clearer understanding of skin barrier function, and of the physicochemical, pharmacokinetic and physiological factors which underpin the feasibility of transdermal administration. Novel, non-invasive approaches to enhance and control drug transport across the skin are under intensive investigation, and some technologies, e.g. iontophoresis, have reached true maturity. The "local", subcutaneous delivery of drugs (for example, to underlying muscle and other tissues) is gaining increasing acceptance, and new opportunities in this under-subscribed area may be envisaged.