How do topical medications treat things that are not superficial, like headaches or cramps?

Question

How do topical medications treat things that are not superficial, like headaches or cramps?

In: Biology

Answer 1

The skin is not an impermeable barrier. While effective at keeping things out, it has holes through sweat glands and very narrow passages between cells. Because of this, medications especially small, lipophilic ones can pass through and enter circulation. The rate of the medication entering can also be altered through heat, surface area, methods to enhance permeability (such as iontophoresis) and other chemicals that increases permeability of the skin (such as alcohol).