The Association of National Advertisers has joined three pharmaceutical companies in suing the federal government to block a new rule requiring drug makers to disclose the list prices of their products in ads to consumers, CNBC reported Friday.

The regulation by the U.S. Department of Health and Human Services, which was finalized in May, required drug makers to disclose prices in drug ads targeted at consumers. The requirement is part of the Trump administration's efforts to reduce drug prices.

In the lawsuit, ANA and the drug companies say the prices that appear in the ads do not reflect what consumers actually pay because they fail to take into account rebates and discounts offered by drug makers, according to CNBC.

"Not only does the rule raise serious freedom of speech concerns, it mandates an approach that fails to account for differences among insurance, treatments and patients themselves, by requiring disclosure of list price," one of the plaintiffs, the drug maker Amgen, said in a statement.

In addition to ANA and Amgen, the other plaintiffs are Merck and Eli Lilly. https://cnb.cx/2ImfkEE

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