Months earlier, the agency released a report alleging the companies drove up the costs of some medications, including insulin.

Three companies that process about 80% of prescriptions in the United States — Caremark, Express Scripts and OptumRx — have engaged in anticompetitive practices that spur price increases, the

The Federal Trade Commission on Friday filed a lawsuit over insulin prices against the three largest pharmaceutical middlemen that negotiate prescription drug prices, arguing that the companies artificially inflate the costs of the lifesaving diabetes drug for patients.