You enter a small conference room with about 9 or 10 other students who were also invited to the interview and that is when you guys have 45 minutes to write an essay. You have to choose one of the two prompts that they give you. The topic is different for most and it usually is about some current issue of pharmacy or healthcare in general. They just want to see if you can form your ideas on paper with correct grammar and whatnot. I finished the essay in 10 minutes, so you shouldn't really have too much of a problem either.
After that you get a break, and one of the staff members will give a presentation about financial aid. Later everyone will walk to the faculty building where you get to meet the Dean and converse with her. It is after the meeting with the Dean is where everyone will be split into 2 groups and go to separate rooms where the interviews will take place. You'll be facing 4 or 5 students at the same time, and the interviewers are 2 professors and one 4th year pharm student who's on the Dean's list. If you really want to get an idea of what the questions are, go to the SDN interview feedback website.
Interview lasts about an hour and then you'll get the tour and then lunchtime. That's pretty much how it will go down. Good luck to you!