The FTC action would target often high costs by trying to curb rebates it says drug makers pay to steer patients to their brand name products.

The Federal Trade Commission is getting ready to sue big health care companies, claiming that they are illegally maximizing profits by steering patients to high-cost drugs, according to four people with direct knowledge of the case discussions.

The pending case would target large pharmaceutical intermediaries owned by UnitedHealth Group, CVS and Cigna, claiming that they pushed patients to brand-name drugs, including insulin, according to the four people.

Lawmakers on Capitol Hill, federal regulators and patient advocates have focused on a key profit source for the middlemen: the rebates drug companies pay to get certain medications on a list of covered drugs. They say those rebates can inflate the cost of drugs.