Ligand Pharmaceuticals Incorporated (NASDAQ: LGND ) partner GlaxoSmithKline (NYSE: GSK ) announced today that the U.S. Food and Drug Administration (FDA) has approved PROMACTA for the treatment of thrombocytopenia (low blood platelet counts) in patients with chronic hepatitis C to allow them to initiate and maintain interferon-based therapy. PROMACTA is the first supportive