Sanofi asks U.S. court to block generic blood thinner

WASHINGTON, July 26 (Reuters) - Sanofi-Aventis SASY.PA on Monday asked a U.S. court to block the approval of a generic version of its widely used blood clot treatment Lovenox, arguing that federal regulators improperly approved the medicine last week.

The U.S. Food and Drug Administration on Friday cleared the first generic version of Lovenox for the Sandoz generic drug unit of Switzerland's Novartis AG NOVN.VX, which is allied with smaller partner Momenta Inc MNTA.O.

Sanofi asked the U.S. District Court for the District of Columbia for a temporary restraining order and a preliminary injunction that would require the FDA to withdraw its approval, arguing the decision was arbitrary and capricious.

The French drugmaker argued that the FDA “failed to ensure that Sandoz’s drug has the same active ingredient as Lovenox” as required by law and that federal regulators improperly allowed Sandoz to rely on Sanofi’s proprietary information.

“If not remedied, FDA’s decision will cause Sanofi-Aventis irreparable harm and may result in entry into the market of a generic product that is not clinically equivalent to Lovenox with respect to safety or efficacy,” Sanofi said in court papers.

The complex nature of manufacturing Lovenox, known generically as enoxaparin, had raised doubts about when a generic version might be approved. However, in January, Novartis said it was making progress with a generic copy, leading to expectations an approval was nearing.

Lovenox is used to help prevent deep vein thrombosis, a condition in which blood clots form in veins deep in the body, especially in the lower leg or thigh.

After last week’s FDA approval, Sanofi saw its shares fall 4.3 percent and said it now expects earnings to drop as much as 4 percent this year.

Lovenox, an injectable medicine that is a version of the drug heparin, was Sanofi’s second-biggest product last year, with sales of 3.04 billion euros ($3.9 billion).

The product had U.S. sales of $2.7 billion last year and is the best-selling hospital medicine in the country, according to Novartis.

A spokesman for Novartis was not immediately available for comment. The company said last week it started shipping immediately after the approval.

The case is Sanofi-Aventis U.S. LLC v. Food and Drug Administration et al, Case No. 10-cv-01255 in U.S. District Court for the District of Columbia.

Reporting by Jeremy Pelofsky in Washington and Lewis Krauskopf in New York; Editing by Phil Berlowitz