Novartis hit three generic drugmakers with a lawsuit in a Delaware federal court for patent infringement over its heart-failure drug Entresto (sacubitril/valsartan).

The generic drugmakers — Alembic Pharmaceuticals, Macleods Pharmaceuticals, and Natco Pharma — submitted separate ANDAs to the FDA in September seeking approval of generic versions of the drug before the expiration of four Novartis patents for the drug.

The patents, issued between 2012 and 2016, were aimed at the drug’s active ingredients, the drug’s specific formulation, and its use for treating heart failure.