UPDATE 4-US clears generic version of Sanofi blood thinner

* Lovenox was Sanofi’s second-biggest seller last year

* Sanofi shares close down 4.3 percent

* Sanofi cuts its 2010 financial outlook

* Shares of Novartis partner Momenta climb 81.9 pct (Recasts, adds Sanofi comment)

By Lewis Krauskopf

NEW YORK, July 23 (Reuters) - U.S. health regulators approved on Friday a generic version of the widely-used Sanofi-Aventis blood clot treatment Lovenox, leading the French drugmaker to cut its 2010 financial outlook.

The U.S. Food and Drug Administration said approval of the first generic version of Lovenox was granted to the Sandoz generic drug unit of Switzerland's Novartis AG NOVN.VX, which is allied with smaller partner Momenta Inc MNTA.O. Shares of Momenta soared 81.9 percent.

Sanofi SASY.PA, which saw its shares fall 4.3 percent, said it now expects earnings to drop as much as 4 percent this year.

“Clearly, it’s bad news for Sanofi,” said Paul Diggle, an analyst at Ambrian Partners in London.

“They had conceded this was highly possible but, because of the uncertainty, they hadn’t got it in their 2010 guidance.”

The hit to Sanofi came as a source familiar with the matter said the French drugmaker approached biotech company Genzyme Corp GENZ.O> about a possible acquisition. [ID:nN23155324]

Citing the approval of a generic rival to its second-biggest selling product, Sanofi said on a preliminary basis it expects 2010 earnings per share to be flat to down 4 percent versus 2009. In April, it had projected earnings growth of between 2 percent and 5 percent.

Sanofi said in statement that is was concerned about the safety of the generic drug, since it “has not been subjected to extensive clinical trials.” The drugmaker also said it would be “considering all appropriate legal options.”

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.

Shares of Teva Pharmaceutical Industries Ltd TEVA.TATEVA.O, which also is seeking to sell a generic form of Lovenox, closed down 8.6 percent on Nasdaq.

The approval of the complex medicine spooked Teva investors, who feared the FDA now might be willing to approve a generic version of Teva’s blockbuster multiple sclerosis drug, Copaxone, which also is seen as complicated to make.

Momenta and Novartis also are seeking U.S. approval of a generic Copaxone, and Momenta said on a conference call on Friday it was working with the FDA on its Copaxone application.

Teva in a statement said any potential generic version of Copaxone would need to be evaluated with full-scale clinical trials, given Copaxone’s complexity.

Teva also said it believes its generic Lovenox meets FDA criteria and is approvable.

Along with Teva, a partnership of Watson Pharmaceuticals Inc WPI.N and Amphastar Pharmaceuticals also is seeking approval for a generic Lovenox. An FDA spokeswoman said the agency could not comment on the status of other applications.

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.

Novartis said its generic will be a substitute for the brand version and it started shipping immediately after the approval.

The approval of the generic Lovenox was a major validation for Momenta, which started work on the product in 2002.

Following the approval, Rodman & Renshaw analyst Simos Simeonidis said Momenta would be a desirable acquisition for generic drugmakers and large pharmaceutical companies with an interest in generics.

Momenta shares closed up $9.77, or 81.9 percent, to $21.70 on Nasdaq. Novartis shares were unchanged in Swiss trading.

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.

Clots can then travel through the bloodstream and wind up in the lungs, where the clots -- known as pulmonary emboli -- can create deadly blockages.

At least 100,000 cases of pulmonary embolism occur each year in the United States, according to the National Heart, Lung, and Blood Institute. (Reporting by Lewis Krauskopf; additional reporting by Ransdell Pierson in New York, Ben Hirschler in London and Deena Beasley in Los Angeles; editing by Robert MacMillan, Andre Grenon and Carol Bishopric)