This system is designed and not yet in the game.
Alchemy adds no second rule set. A potion is an enchantment cut down to its smallest legal shape: a cell, one glyph, no gate, no conduit — one discharge, spent the moment it is drunk. The drinker supplies nothing, no beat and no skill; everything the potion is was decided when it was made.
What fits in a bottle
Only effects that act on the drinker. Anything with a direction — fire, anything thrown or aimed — stays a cast. A potion is magic for people who are not the caster, which is precisely what makes it worth carrying.