Trump said on Wednesday that pharmaceutical companies were "getting away with murder" in what they charge the government for medicines, and promised that would change, knocking down U.S. drugs stocks.

Late on Wednesday, a U.S. law firm filed a securities class action lawsuit on behalf of Lehigh County Employees' Retirement System against Novo Nordisk.

The lawsuit alleges that the Danish company, which gets around half its revenue in the United States, of making misleading earnings forecasts, the law firm, Bernstein Litowitz Berger & Grossmann, said in a press release.

"We're aware of the complaint. It wouldn't be appropriate for us to comment at this time since we're evaluating the allegations in the complaint," Novo Nordisk said in an email to Reuters.

Novo Nordisk's shares were 5.3 percent lower at 241.90 at 0922 GMT (4:22 a.m. ET), while the European index of healthcare stocks was down 2.0 percent.

"This is a double whammy for Novo Nordisk today, and both factors are behind the share price reaction," analyst Michael Friis Jorgensen from Alm. Brand Bank said.

(Editing by Vyas Mohan and Jane Merriman)

By Teis Jensen