COLUMBUS, Ohio - A lawsuit filed by Ohio Attorney General Dave Yost has led to changes at a popular prescription benefit company.

Yost filed a lawsuit against Express Scripts, Prime Therapeutics and five others for allegedly using a little-known Switzerland-based company to illegally drive up drug prices.

Yost said Pharmacy Benefit Management (PBM) companies are "modern gangsters" and were designed to negotiate on behalf of employers and consumers after Big Pharma was criticized for overpricing medications.

The lawsuit says Express Scripts marketed its ability to leverage its significant market power to get lower drug prices but in reality the promise was "knowingly false."

Just weeks after the lawsuit was filed, Cigna Group - the parent company of Express Scripts - they decided to be more transparent, according to Yost's statement.

Yost said the move does not settle the lawsuit, however.

"It's full steam ahead in court," Yost's statement said.