Why cant drug companies make Aspirin more soluble using its salt especialy in dissolvable formulations?

When you dissolve aspirin, especialy when its in soluble forms.. codis, anadin extra soluble etc. The aspirin most of the time sits at the top undisolved! Why dont drug companies make 'a' salt of aspirin like aspirin phosphate, hydrochloride, sulphate, tartrate, citrate, succinate, sodium? Or is there some piece of chemistry or other reason that prevents this being possible? am chem student and cant figure why not make aspirin more soluble with a salt, thanks!