An antitrust lawsuit filed in a federal court in New York claims AstraZenica struck a deal with generic drugmakers to hold off on launching versions of its anti-psychotic drug Seroquel XR.

The proposed class action suit, filed by drug distributor J.M. Smith Corp., accuses AstraZenica of working with generic drugmakers Handa Pharmaceuticals and Accord Pharmaceuticals  to delay release of their generic versions of Seroquel XR for five years. In exchange, AstraZenica would delay releasing its own generic version of the drug by six months to May 1, 2017, according to the filing in the U.S. District Court for the Southern District of New York.

The delay gave Handa and Accord a significant competitive advantage and artificially inflated costs for both branded and generic versions of the drug, J.M. Smith claims. The company is seeking to recover overpayments as a result of the alleged scheme.