For the cocktail bottle, 1 works, but 2 doesn't. Rather than 2 I would prefer "the cocktail is easily made with this bottle". For the medicine I would prefer the similar sentence "the medicine is best taken on an empty stomach."
I think that "it's best to be taken" sounds a little awkward, though I would not say it is actually incorrect. "It's best to take on an empty stomach" doesn't work, but you could use "it's best to take the medicine on an empty stomach" instead.
I think the form "this medicine is best taken on an empty stomach", "pasta is easily made with noodles", "arithmetic is easily done with a calculator" works most of the time.
Another problem is why sentence 1 works, but the apparently similar sentence "The medicine is best to take on an empty stomach" doesn't. I think that this is because the word "best" is relating back to the medicine instead of forward to the empty stomach. The statement reads as though it is comparing the medicine with other things that may be good to take on an empty stomach, but the advice really means that the medicine works best if taken on an empty stomach (instead of a full one).