In honor of March Madness, The Motley Fool's health-care team has assembled its own bracket consisting of the 16 largest pharmaceutical and biotech stocks on the market. The series gets under way with a tough matchup between two struggling giants of the pharmaceutical industry: AstraZeneca (AZN -0.24%) and Merck (MRK 0.15%). To learn the bull and bear cases for each stock -- and to see which stock will move on to the Elite Eight -- watch the following video.