I have read that ketamine is a street drug being swallowed by many Brits and that it destroys their bladders. Given that the hormones are well absorbed into the blood from the skin, what exactly stops the ketamine from being absorbed, as you state in your book?
Differing things have differing absorption, with some penetrating more locally and some with more systemic effects. Even orally, the ketamine has very poor absorption. The blood levels reflect this, and as ketamine is an anesthetic, the effects of significant blood levels would not be subtle. So the bottom line is that I don't know why they absorb differently than the hormones (good question), but they do;-)