The company, founded in 1942, listed debts of $728.3 million and assets of $236.6 million in a filing in bankruptcy court in New York.

The company blamed the bankruptcy on its "inability to realize the full value of Makena," the drug to help avoid premature births, because of the Food and Drug Administration's refusal to enforce orphan drug marketing exclusivity for it, Thomas McHugh, the company's treasurer and vice president, said in declaration filed with the court.

The company also said it was hurt by restrictions on reimbursements imposed by state Medicaid agencies.

McHugh also blamed restrictions on manufacturing and marketing of its other products that were imposed as a part of a 2009 consent decree with the Justice Department after a recall of products, including some tablets that may have been oversized.

In 2010, KV's Ethex unit pled guilty to failing to alert drug authorities about pill manufacturing problems, and agreed to pay a criminal fine of $23.4 million. The following year, former CEO Mark Hermelin pled guilty to violating drug labeling laws.

(Reporting by Ann Saphir; Editing by Vicki Allen)