In a pharmacy space is typically a premium. Short of knowing exactly what you're running it's hard to recommend something. However, knowing most medical applications of technology, there's not much computing involved, mostly UI. I would recommend something like this.
Intel DN2820FYKH, 4GB RAM, and like a 64-128GB SSD. You shouldn't need a CD drive for day to day operations so a USB one to move from one NUC to another as needed is plenty. Beyond that, just mount these to the back of the LCDs and you got something that's fast enough and space efficient.