Massachusetts and 19 other states filed a federal lawsuit yesterday against six pharmaceutical companies, claiming they illegally conspired to artificially inflate prices and reduce competition for two generic drugs.

The Connecticut-led antitrust lawsuit alleges Heritage Pharmaceuticals Inc., Aurobindo Pharma USA Inc. and four other companies engaged in price-fixing for doxycycline hyclate delayed release, an antibiotic, and the oral diabetes medication glyburide.

The suit, filed in U.S. District Court in Connecticut, states that senior male executives schemed during a steakhouse dinner, and female sales representatives discussed competitively sensitive information at “girls night out” and “women in the industry” events. Drug company reps also colluded via email, phone and text messages, according to the complaint.

Connecticut began its investigation into suspicious generic drug price increases in 2014 and developed “compelling evidence of collusion and anticompetitive conduct across many companies that manufacture and market generic drugs in the United States,” Attorney General George Jepsen said. He singled out New Jersey’s Heritage as the “principal architect” of the alleged conspiracies.

The U.S. Department of Justice Wednesday filed criminal charges against a former Heritage CEO and vice president for alleged price-fixing and bid-rigging related to the same two drugs. Both men are named in the 20-state lawsuit. Heritage said it fired them in August and is cooperating fully with the DOJ.

U.S. generic drug sales reached an estimated $74.5 billion in 2015. Generics account for about 88 percent of all U.S. prescriptions.

“Generic drugs play a vital role in keeping health care costs down and making medication affordable to those who need it, and companies that fix prices to illegally profit and drive up prescription drug costs must be held accountable,” Massachusetts AG Maura Healey said in a statement.