How hard will it be for insurers to curb the use of pricey life-saving medicines? Here's a potential answer: The $1,000-a-day hepatitis C pill from Gilead Sciences is on track to notch among the biggest sales to date for the first year of a newly approved drug. Our story examines the market potential of the new medication as well as it how it will resonate with insurers, whose bottom lines, we note, are already being threatened. Some 3.2 million people in the U.S. are believed to carry hepatitis C—many of whom contracted it through intravenous drug use. The new drug, called Sovaldi, which carries a list price of $84,000 for a 12-week course of treatment, is spurring pushback among some payers and public officials, who say the price is too high for something with such a broad potential market.