Sanofi-Aventis’ share price slipped by 7% during trading in New York yesterday, with almost 15 times the average number of shares traded on a day that saw market entry of generic versions of its top-selling clot-busting agent, Lovenox (enoxaparin), move a step closer to reality.

In a statement released yesterday, the French drugmaker said that a US district court in California had, earlier this week, accepted an inequitable conduct claim filed by Amphastar Pharmaceuticals as part of a patent infringement lawsuit. Sanofi-Aventis says that, should the court formally accept the ruling, the 30-month stay on US Food and Drug Administration approval of a copycat Lovenox would be lifted. Although this would signal the potential green light for generic versions of the product, Sanofi-Aventis says it has not learned of any FDA approval of the requests to produce a generic version of Lovenox by either Amphastar or its co-defendant, Teva

Perhaps not surprisingly, Sanofi-Aventis says it will appeal this ruling and will “vigorously defend its intellectual property rights covering Lovenox.”

Back in 2003, Aventis – which was acquired by Sanofi-Synthelabo last year – filed patent infringement lawsuits in the US after generics companies Amphastar and Teva sought approval for their copycat versions of Lovenox, asserting that the main patent covering the drug – due to expire in 2012 – was invalid [[05/08/03c]], [[26/06/03a]], [[28/07/03d]].

- Meanwhile, although the firm’s share price took a knocking, investors at Deutsche Bank remain confident that there is a very low probability the FDA will approve a substitutable generic, given Lovenox’ “incomplete characterisation and its sources of clinical activity.” However, pending a ruling from the FDA on this issue, the analysts have reduced their price target to €69 euros from €70 to allow for the greater risk of generic competition.