transdermal

/ˌtrænzˈdɜːrməl/
adjective
  1. Relating to the delivery of a substance (such as a drug) through the skin and into the bloodstream.
    • The doctor prescribed a transdermal gel for hormone therapy.
    • Nicotine patches are a common transdermal treatment for quitting smoking.
    • Transdermal drug delivery is often preferred because it avoids the digestive system.