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 1.11%). He also discusses Merck's (MRK 3.32%) latest stumble, a failed study that may get an approved drug pulled from the market.