Although some drugs have inherent side effects that cannot be eliminated in any dosage form, many drugs exhibit undesirable behaviors that are specifically related to a particular route of administration. One recent effort at eliminating some of the problems of traditional dosage forms is the transdermal delivery system. Oral administration of drugs initially through powders extracts, and liquids has been around since before recorded history and more recently through tablets and capsules. Injectables came into being about 130 years ago, but have only been acceptable since the development of a better understanding of sterility. Topical application has been used throughout the centuries mostly in the treatment of localized skin diseases. Local treatment only requires that the drug permeate the outer layers of skin to treat the diseased state and it is hoped this occurs with little or no systemic accumulation.