 The study says patients are getting caught between drug companies and their health insurance. NPR's Sydney Lupkin explains. Insurance companies' lists of covered drugs, called formularies, are shrinking. On average, Medicare formularies only cover a little more than half of the drugs approved by the FDA. But in 2010, they covered nearly three-quarters of them. That's according to new research by GoodRx, a website that helps patients find discounts on prescription drugs.