It seems at the moment we have to invent something for it. There are lots of source materials around, which can be used as a basis, depending on how much power you want to give to alchemy. I remember some books about plants and other ingredients for alchemy, made by 3rd parties for other game systems, which could be useful, if you like it "realistic".
The Rolemaster Alchemy Companion can serve as source for ideas (only ideas, the rules are 100% incompatible), or the various potions/powders/ointments around in the incarnations of AD&D/D&D (again, only as ideas for effects).
I have not had a chance to look, but maybe books from other skill systems might help. GURPS might have something usable in it, and Das Schwarze Auge (don't know if that is available in english, should translate as The Dark Eye).
There were potions in RQ 3, but they had to be enchanted using permanent POW (and did mostly common magic stuff), which made them kind of rare, and is probably not what players would be looking for.