Vivus Inc., of Mountain View, Calif., said it filed a lawsuit in the U.S. District Court for the District of New Jersey against Hetero USA Inc. and Hyderabad, India-based Hetero Labs Ltd. in response to an abbreviated new drug application (ANDA), filed by Hetero, seeking to market and sell generic versions of the currently approved doses of Stendra (avanafil) tablets prior to the expiration of U.S. Patents 6,656,935 and 7,501,409, which are listed in the FDA’s Orange Book.