Two Democratic lawmakers are calling on the Federal Trade Commission to investigate if Mylan Pharmaceuticals violated antitrust laws to make sure that EpiPen dominated the market for the life-saving allergy drug.

Sens. Richard Blumenthal of Connecticut and and Amy Klobuchar of Minnesota wrote a letter on Tuesday to FTC Chairwoman Edith Ramirez charging that the contract for Mylan’s “EpiPen4Schools” discount program required some schools to sign a contract agreeing not to buy any products from competitors for a year, which is “conduct that can violate the antitrust laws when taken by a monopolist.”