In this video, Motley Fool health-care analyst David Williamson takes a closer look at what has propelled Aegerion Pharmaceuticals (NASDAQ: AEGR) to new heights and what it means for its potential competitor Isis Pharmaceuticals (IONS -1.55%). He also discusses Merck's (MRK 1.77%) latest stumble, a failed study that may get an approved drug pulled from the market.