Patients with hepatitis C have yet another advanced treatment option, as the Food and Drug Administration on Thursday approved a new once-a-day pill developed by drugmaker Merck. The FDA said Merck can begin marketing Zepatier for patients with two of the subtypes the liver-destroying virus, types 1 and 4. The combination pill includes the medications elbasvir and grazoprevir, which attack the virus in two different ways.