Transdermal drug delivery provides excellent control of the rate of delivery directly into the bloodstream. It also offers a predictable pharmacokinetic profile and constant drug levels over extended periods of time without the extreme peak/trough fluctuations inherent in oral administration. And discontinuation of therapy can be achieved immediately by simply removing the patch. The total market for TDD products in the US, major European markets, and Japan was approximately $2.5 billion in 2001 (this does not include a $1.4 billion market for plaster/poultice products in Japan).
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