Groton — Only about 30 new drugs are approved each year in the United States, and tiny Amarin Corp., with research-and-development headquarters in the city, now has one of them.

The U.S. Food and Drug Administration has approved Amarin's fish-oil derived medication Vascepa for the treatment of heart disease, the company said Thursday. Vascepa is the commercial name for the drug previously known only as AMR101.

"FDA approval of Vascepa represents the introduction of an important new treatment option for patients," Joseph Zakrzewski, chairman and chief executive of Amarin, said in a statement.

Amarin said it is still considering its options for marketing Vascepa, including a possible sale of the company, a strategic collaboration, or self-commercialization.

Vascepa will be launched in the first quarter of 2013. Amarin said it is still awaiting a decision from the FDA on whether it will be granted five-year exclusivity to sell the drug as a new chemical entity.

"We are now focused on continued commercial preparations for Vascepa, which includes ... finalizing the introduction of Vascepa to managed care plans to gain formulary access, building up inventory levels and coordinating other pre-launch marketing activities," Zakrzewski said.

The drug, an ultra-pure omega-3 fatty acid that was fast-tracked by the FDA, lowers the level of fat in the blood of patients at high risk of heart disease. It is expected to compete with the GlaxoSmithKline medicine Lovaza, which recorded about $1 billion in sales last year.

The approval, announced late Thursday, allows Amarin to market Vascepa only to patients with very high levels of fat in their blood. Amarin is also testing the medicine on people with moderately high levels of so-called triglycerides and expects to seek approval for marketing the pill to that populations if results show a positive effect.

Earlier in the week, the European Patent Office issued a notice saying it intended to grant Amarin's patent application for the new medicine.

Ironically, the Ireland-based Amarin's crowning achievement rose out of the ashes of one of the company's most disappointing moments. In 2007, Amarin's lead experimental medicine, Miraxion, failed in a trial focusing on Huntington's disease, but the company soon retraced its steps and used the key ingredient of Miraxion to develop a new drug, AMR101, that had a long history of fighting cardiovascular disease in Japan.

The company's 20 or so local employees include several former Pfizer Inc. scientists, including Paresh Soni, Amarin's current head of development. Amarin transferred its R&D operations to Mystic in 2008, then moved into Groton office space at 475 Bridge St. earlier this year. The company's U.S. presence operates as Amarin Pharma Inc.

So far this year, only 14 new drugs have been approved by the FDA. Pfizer, with about 5,000 times Amarin's number of employees, usually sees only one or two new drug approvals each year.

Trading in Amarin's stock, listed on the Nasdaq exchange under the symbol AMRN, had to be stopped Thursday afternoon after fluctuating wildly throughout the day, finishing at $15.31 a share, up 5 percent.

l.howard@theday.com