ABSTRACT
Drug delivery technologies strive to balance the ability to deliver drugs effectively with the ability to do so in a patient-friendly manner [1,2]. Injection or infusion through a hypodermic needle is the gold standard for effective delivery, since large amounts of drug of any size can be administered with controlled kinetics. However, the pain and inconvenience of needles have motivated alternative drug delivery approaches, such as transdermal drug delivery. By transporting drug across the skin either by passive diffusion or combined with chemical, electrical, ultrasonic, or other enhancers, transdermal delivery provides controlled release of drugs from a patient-friendly patch [3,4]. However, this approach is severely limited, because the skin’s great barrier properties prevent most drugs from crossing skin at therapeutic rates.
