I called the pharmacist and he said not to worry about the Prevacid and Cipro interacting. I think when they say antacid they mean TUMS or Maalox , that my guess, since the pharmacist said not to worry about the Prevacid. The problem with the vitamin is it can affect the absorption of Cipro so he said you would not want to give them together.
I plan on giving Maggie the Cipro with breakfast , vitamin at lunch and Cipro before bed(with a snack).
Calcium from milk also binds with Cipro, but she usually does not drink milk in the morning anyway. She does have milk at dinnertime, though.