Sanofi-Aventis is heading to the courts in a fresh bid to defend its patents on Plavix just as the Swiss firm Schweizerhall says its generic version of the blood-thinning blockbuster has been approved by German regulators.

The French drugmaker issued a statement saying it has become aware of the registration of clopidogrel besylate in Germany with the country’s regulatory authority, the BfArM. However the firm notes that these registrations refer to a different salt of clopidogrel than the one found in Plavix/Iscover (clopidogrel bisulfate) “and the products are labelled only for a limited number of indications when compared to Plavix”.

Sanofi said that it is “convinced that these registrations have been obtained in violation of applicable laws and it has already filed legal action”. The firm concluded by saying that will continue to “vigorously defend its rights, including patent and regulatory data protection”.

Despite the legal threat, Schweizerhall was pleased to announce the German approval for its version of clopidogrel, developed by its Cimex unit. It has signed up Novartis’ Sandoz unit and Ratiopharm of Germany to sell the product, though the Basel-based group declined to give any launch date.

Plavix annual sales in Germany are around 340 million euros and Schweizerhall noted that it also hopes to get marketing authorisation in Luxembourg before the end of June.

Sanofi pulls Aquilda filing in EU
Meantime, for the second day running, Sanofi has withdrawn a second European marketing authorisation application in as many days, this time for Aquilda (satavaptan), a new treatment for hyponatremia, where the body’s blood sodium level falls below normal.

The drug was submitted to the European Medicines Agency on May 30 last year but Sanofi now says that it is pulling the application after the agency’s Committee for Medicinal Products for Human Use asked for additional information on the safety and efficacy of satavaptan. The French drugmaker says that it is putting together that information but the results will not be available before 2009.