The Federal Trade Commission said pharmacy benefit managers created a "perverse drug rebate system" that artificially inflated the cost of insulin.

Express Scripts, one of the country’s largest pharmacy benefit managers, sued the Federal Trade Commission (FTC) Tuesday and demanded the agency retract a report saying the industry middlemen

At issue is a report released by the FTC in July called: “Pharmacy Benefit Managers: The Powerful Middlemen Inflating Drug Costs and Squeezing Main Street Pharmacies.” Express Scripts claims in the lawsuit that the report “is seventy-four pages of unsupported innuendo” leveled against it and other PBMs.

Express Scripts Inc. on Tuesday sued the Federal Trade Commission in federal court in St. Louis, alleging that a July report made “unsubstantiated, false and biased claims” about the company.

Express Scripts, one of the largest pharmacy benefit managers in the U.S., filed a lawsuit demanding that a recent FTC report on industry middlemen be vacated.