Subjects will have blood work and an intravenous access line (IV) placed for several blood draws during the visit. Subjects will begin fasting at 8pm during the admission, which means they may consume only non-caloric fluids (water, unsweetened black coffee or tea, or sugar-free beverages). The next morning, fasting blood work will be obtained. The subject can then eat breakfast and will receive the study drug, Ravicti. The total time of fasting will be 12 hours.