Dr. David Edwards , associate professor of chemical engineering , recently published a theory and set of equations that describe how medicine gets through your skin via the transdermal patches currently on the market, such as those for motion sickness, smoking cessation, or hormone replacement therapy. Edwards developed the equations while he held a postdoctoral position at the Massachusetts Institute of Technology. These equations are the first to be equally applicable to all types of transdermal drug delivery on the market as well as those still on the drawing board that use assistance from ultrasound and electric fields. Taking medicine through your skin is preferred when a drug is difficult to take by mouth or when passage through the liver would result in breakdown of the drug.
Transdermal delivery avoids the liver as well as the mouth.
Unfortunately, Edwards says, it is difficult to deliver medicine transdermally without harming the skin. Currently, there are only nine drugs on the market that use transdermal delivery. However, using his new theory and equations, Edwards has been able to model specific processes in transdermal transport that can be enhanced by electric fields or by ultrasound. The new information should enable pharmaceutical researchers to develop formulations that allow more drugs to be delivered transdermally. For example, Edwards and his colleagues found that the new theory and equations can predict whether electric fields will enhance the passage of specific medicines through the skin.