Brewing elixirs is a dangerous, often fatal pursuit. The wrong combination of ingredients is poisonous, or worse. The larger problem, however, is that apothecaries are loathe to share their secrets with one another, for fear of losing their business advantage. Which means that each and every practitioner has their own specific set of recipes for creating a desired effect.
This elixir seems to have a digestive effect on the drinker, allowing them to quickly process foods and other concoctions taken through the mouth.
Ironically, perhaps, this elixir is most often taken by apothecaries (or their servants) when they are about to test a new concoction.