Amphastar Pharmaceuticals, Inc. won a patent dispute brought against the company by Momenta Pharmaceuticals, Inc. and Novartis AG's generics unit, Sandoz International GmbH.

In affirming an earlier verdict by a federal jury, the U.S. District Court for the District of Massachusetts noted that Momenta's U.S. patents covering a method to manufacture a generic version of the medicine Lovenox were invalid and unenforceable.

Momenta and Sandoz filed a lawsuit against Amphastar in 2011 after the U.S. Food and Drug Administration approved Amphastar's generic version of the blood thinner, which is sold as Lovenox by Sanofi.

The court also denied a motion by Momenta and Sandoz to dismiss Amphastar's antitrust lawsuit against the companies. The lawsuit alleges that both companies prevented Amphastar from selling an injectable version of enoxaparin sodium, the main component of Lovenox, and thus excluded a cheaper alternative of the drug from entering the market.

"We are very happy to receive the court's final judgment in Amphastar's favor as well as the court's denial of Momenta's and Sandoz's motion to dismiss our antitrust lawsuit. We can now proceed to file a motion to collect the $100 million bond in the patent case and proceed to assert our treble damages under antitrust law," Amphastar CEO Jack Zhang said in a statement.