"Yes, I have had one other interview at this time and am awaiting word on the next steps. While I'm confident in how I performed in that interview, I want you to know that I would consider this opportunity the best for me and my family. Your company has one of the top industry reputations and I'd be so excited for the opportunity to represent you in this market."

This is a time to be honest with your interviewer. If you are applying to and/or interviewing for any other pharmaceutical sales position, you'll want to keep the ball in your court and show that you are desired by other employers. This could also be a great tactic to negotiate your salary. If they want you and you are interviewing with others they may offer you more to stay with them. If this is the only position you are considering at this time, make sure to reiterate that this is your dream job and company to work for.