The Federal Trade Commission and New York Attorney General Letitia James said in a lawsuit filed Monday that former pharmaceutical CEO Martin Shkreli — dubbed the "Pharma Bro" — created an illegal monopoly by raising the price of the drug Daraprim by more than 4,000% "overnight."

Vyera Pharmaceuticals, formerly Turing Pharmaceuticals, was also charged in the suit regarding the drug, which is the only FDA-approved medication to treat toxoplasmosis.

Daraprim was "cheap and accessible for decades" until Vyera purchased the rights to the drug and increased its price, James said in a statement.

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The Federal Trade Commission and New York Attorney General Letitia James charged "Pharma Bro" Martin Shkreli in a lawsuit filed on Monday, alleging that he and Vyera Pharmaceuticals stifled competition to protect "exorbitant, monopolistic pricing" on the drug Daraprim.

Skhreli and Vyera — formerly called Turing Pharmaceuticals — increased the price of Daraprim from $17.50 to $750 per tablet after purchasing the rights to the drug in 2015, the FTC said in a statement. The drug had been affordable for over 60 years, the FTC said, until Shkreli and the firm bought the drug and raised the price.

Following a multiyear investigation, James and the FTC allege that Shkreli and Vyera illegally maintained a monopoly on the drug by restraining distribution to prevent other manufacturers from creating a generic version of the drug.

The price increase of over 4,000% held the drug "hostage" and forced consumers to make "difficult and risky decisions," James said in a statement.

As the only FDA-approved treatment for toxoplasmosis, Daraprim is "the gold standard treatment for a rare, potentially fatal parasitic infection," the FTC said in a statement.

The FTC voted unanimously to file the complaint. Vyera parent company Phoenixus AG and former chief executive Kevin Mulleady are also named in the suit, filed in the US District Court for the Southern District of New York.

"We filed this lawsuit to stop Vyera's egregious conduct, make the company pay for its illegal scheming, and block Martin Shkreli from ever working in the pharmaceutical industry again," James said.

Vyera did not immediately respond to a request for comment.

Skhreli was previously sentenced to prison for a separate case of securities fraud, in which he was widely criticized as arrogant, and lost an appeal in July to overturn his sentence.

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