My interview there last year was really conversational, with open ended questions.
Just lead the interview where you want it to go. If they ask you a few things about yourself, mention some of your hobbies, past-times, where you grew up, maybe a few things you want them to ask you about. Also, be prepared to answer the typical questions:
"why medicine?"
"What do you want to do with medicine"
"why will you be a good doctor"
My interviewer was very straightforward. If you're worried, see if you can't schedule a quick mock interview at your school's advising/career center, and also, browse the interview feedback for questions and experiences at Drexel.
One thing that really helps me is to come up with a list of experiences that can substantiate certain qualities or thoughts I may have. Then I try and organize some key points, concepts, ideas I want to bring up for each question and just run with it. I suck at verbal organization without some practice, so I try to organize myself with a point form outline on paper. Then I practice in front of the mirror, giving myself a certain amount of time to answer the question.
Most people, say just be yourself, but I know how disastrous things can go if I don't prepare...I don't know if any of what I said above is helpful, but one of the best things you can do is go over different possible questions they can ask you and try and figure out which questions make you nervous or uncomfortable and spend a bit of time trying to come up with answers or ideas for those questions. If you think you have a weak area...work and it and maybe try practicing either alone or with a friend who has already been on an interview...
Best of luck!!!