I have no clue for an answer but salvinorin a is not active orally. It is active with the buccal administration (chewing in the mouth), is your thinking that transdermal administration would bypass metabolism like buccal? I don't even know how a nicotine patch works unfortunately so can't help much.
i don't think it's a great idea to use DMSO on your skin. i suppose it could be done with sterile technique
Salvorin A molecule is pretty big as things go. I dunno if it is too big to go through the skin by itself. I know there are modifications you can add to the patch to allow larger molecule sized drugs to get through, though.
well, with DMSO, i believe bacteria can get in, which are enormous compared to a salvinorin A molecule
